WO2010061696A1 - Conductive member and solid state polymer fuel cell using same - Google Patents

Conductive member and solid state polymer fuel cell using same Download PDF

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Publication number
WO2010061696A1
WO2010061696A1 PCT/JP2009/068048 JP2009068048W WO2010061696A1 WO 2010061696 A1 WO2010061696 A1 WO 2010061696A1 JP 2009068048 W JP2009068048 W JP 2009068048W WO 2010061696 A1 WO2010061696 A1 WO 2010061696A1
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WIPO (PCT)
Prior art keywords
layer
conductive
intermediate layer
conductive carbon
metal
Prior art date
Application number
PCT/JP2009/068048
Other languages
French (fr)
Japanese (ja)
Inventor
友克 姫野
宮澤　篤史
基 柳沼
山本　啓介
岡田　圭司
山崎　努
沼尾　康弘
聡彦 津田
Original Assignee
日産自動車株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from JP2008301309A external-priority patent/JP5332550B2/en
Priority claimed from JP2008303223A external-priority patent/JP5287180B2/en
Priority claimed from JP2008303217A external-priority patent/JP5332554B2/en
Priority claimed from JP2008303219A external-priority patent/JP5353205B2/en
Priority claimed from JP2009142600A external-priority patent/JP5439965B2/en
Priority to BRPI0921570A priority Critical patent/BRPI0921570A2/en
Priority to US13/130,979 priority patent/US8974983B2/en
Priority to EP09828945.7A priority patent/EP2357655A4/en
Priority to RU2011126135/07A priority patent/RU2472257C1/en
Priority to CN2009801473048A priority patent/CN102224550B/en
Application filed by 日産自動車株式会社 filed Critical 日産自動車株式会社
Priority to KR1020117014342A priority patent/KR101211338B1/en
Priority to CA2750783A priority patent/CA2750783C/en
Publication of WO2010061696A1 publication Critical patent/WO2010061696A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B5/00—Non-insulated conductors or conductive bodies characterised by their form
    • H01B5/02—Single bars, rods, wires, or strips
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/02—Details
    • H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
    • H01M8/0204—Non-porous and characterised by the material
    • H01M8/0213—Gas-impermeable carbon-containing materials
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B13/00—Apparatus or processes specially adapted for manufacturing conductors or cables
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/02—Details
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/02—Details
    • H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
    • H01M8/0204—Non-porous and characterised by the material
    • H01M8/0223—Composites
    • H01M8/0228—Composites in the form of layered or coated products
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M2008/1095—Fuel cells with polymeric electrolytes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M8/12—Fuel cells with solid electrolytes operating at high temperature, e.g. with stabilised ZrO2 electrolyte
    • H01M2008/1293—Fuel cells with solid oxide electrolytes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/14—Fuel cells with fused electrolytes
    • H01M2008/147—Fuel cells with molten carbonates
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/02—Details
    • H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
    • H01M8/0247—Collectors; Separators, e.g. bipolar separators; Interconnectors characterised by the form
    • H01M8/0254—Collectors; Separators, e.g. bipolar separators; Interconnectors characterised by the form corrugated or undulated
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/08—Fuel cells with aqueous electrolytes
    • H01M8/083—Alkaline fuel cells
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/08—Fuel cells with aqueous electrolytes
    • H01M8/086—Phosphoric acid fuel cells [PAFC]
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/50—Fuel cells

Definitions

  • the present invention relates to a conductive member and a polymer electrolyte fuel cell using the same.
  • the polymer electrolyte fuel cell has a structure in which a plurality of single cells exhibiting a power generation function are stacked.
  • Each of the single cells includes (1) a polymer electrolyte membrane, (2) a pair of catalyst layers sandwiching the polymer electrolyte membrane, and (3) a pair of gas diffusion layers (GDL) for sandwiching them and dispersing the supply gas.
  • GDL gas diffusion layers
  • MEA membrane electrode assembly
  • MEA which each single cell has is electrically connected with MEA of an adjacent single cell through a separator.
  • a fuel cell stack is comprised by laminating
  • the fuel cell stack functions as power generation means that can be used for various applications.
  • the separator exhibits a function of electrically connecting adjacent single cells as described above.
  • a gas flow path is usually provided on the surface of the separator facing the MEA.
  • the gas flow path functions as a gas supply means for supplying fuel gas and oxidant gas to the anode and the cathode, respectively.
  • metals, carbon, conductive resins, and the like are known as constituent materials for fuel cell separators that require electrical conductivity.
  • the carbon separator and the conductive resin separator it is necessary to set the thickness relatively large in order to secure the strength after forming the gas flow path to some extent.
  • the overall thickness of the fuel cell stack using these separators also increases.
  • the increase in the size of the stack is not preferable especially in an in-vehicle PEFC that requires a reduction in size.
  • the metal separator since the metal separator has a relatively high strength, the thickness can be made relatively small. Moreover, since it is excellent also in electroconductivity, when a metal separator is used, there also exists an advantage that contact resistance with MEA is reduced. On the other hand, metal materials may have problems such as a decrease in conductivity due to corrosion and a decrease in stack output. Therefore, the metal separator is required to improve the corrosion resistance while ensuring its excellent conductivity.
  • Patent Document 1 a metal layer such as Ti or a carbide layer thereof is formed on one surface of a metal substrate of a metal separator, and is composed of graphitized carbon on the metal layer or the carbide layer.
  • a technique for forming a carbon layer is disclosed.
  • Patent Document 2 discloses a technique in which an oxide film of a base material is formed between a base material of a metal separator and a conductive thin film to form an intermediate layer made of a metal element or a metalloid element. .
  • Patent Document 3 discloses a separator in which a carbon-based film containing a composite of metal oxide is formed on a substrate.
  • the crystal structure of the carbon layer is various.
  • the corrosion resistance and conductivity of the separator itself vary due to this.
  • the oxide film disposed on the surface of the base material itself is a highly insulating layer. For this reason, the electrical conductivity in the thickness direction of the separator is lowered.
  • the conductivity in the thickness direction of the separator is reduced or the contact resistance with the gas diffusion layer is increased. Resulting in.
  • the present invention has been made in view of such problems of the conventional technology.
  • the object of the present invention is to provide a conductive member having sufficiently improved corrosion resistance while sufficiently ensuring excellent conductivity in the conductive member, a manufacturing method thereof, and a polymer electrolyte fuel cell using the conductive member. It is in.
  • the conductive member according to the first aspect of the present invention includes a base material, a conductive carbon layer that is located on at least one surface of the base material, and further includes conductive carbon, and the base material and the conductive carbon layer. And an intermediate layer interposed between the D band peak intensity (I D ) and G band peak intensity (I G ) measured by Raman scattering spectroscopy in the conductive carbon layer. And the intensity ratio R (I D / I G ) is 1.3 or more.
  • the polymer electrolyte fuel cell according to the second aspect of the present invention includes the conductive member.
  • FIG. 1 is a schematic cross-sectional view showing a basic configuration of a cell unit of a polymer electrolyte fuel cell using a conductive member (separator) in the first embodiment.
  • FIG. 2 is a cross-sectional view schematically showing the configuration of the metal substrate of the separator of FIG. 1 and the treatment layer formed on the substrate.
  • FIG. 3 is a schematic cross-sectional view showing the surface of the metal separator in FIG. 4A is a cross-sectional view schematically showing a configuration in which an intermediate layer and a conductive carbon layer are provided on both surfaces of a metal substrate in the separator of FIG.
  • FIG. 4B is an enlarged view showing one embodiment of the intermediate layer and the conductive carbon layer.
  • FIG. 1 is a schematic cross-sectional view showing a basic configuration of a cell unit of a polymer electrolyte fuel cell using a conductive member (separator) in the first embodiment.
  • FIG. 2 is a cross-sectional view schematically showing the configuration
  • FIG. 4C is an enlarged view showing another form of the intermediate layer and the conductive carbon layer.
  • FIG. 6A is a schematic diagram showing a three-fold symmetry pattern of an average peak in the measurement of rotational anisotropy in Raman scattering spectroscopic analysis.
  • FIG. 5B is a photograph (magnification: 400,000 times) of a cross
  • FIG. 6B is a schematic diagram showing a two-fold symmetry pattern of an average peak in rotational anisotropy measurement of Raman scattering spectroscopic analysis.
  • FIG. 6C is a schematic diagram showing a pattern that does not show the symmetry of the average peak in the measurement of rotational anisotropy of Raman scattering spectroscopic analysis.
  • FIG. 7A is a graph showing a Raman spectrum when the conductive member B is used as a measurement sample, and the rotation angles of the sample are 0 °, 60 °, and 180 °, respectively.
  • FIG. 7B is a graph showing the average peak of rotational anisotropy measurement for conductive member B.
  • FIG. 8 shows the Vickers hardness of the conductive carbon layer and the sp 3 ratio of the conductive carbon layer in the conductive member in which the Vickers hardness of the conductive carbon layer is varied by changing the bias voltage and the film formation method by sputtering. It is a figure which shows the relationship with the value of.
  • FIG. 9 is a graph showing the results of measurement of contact resistance for conductive members having conductive carbon layers having different R atom values but having different hydrogen atom contents.
  • FIG. 10 is a conceptual diagram of a vehicle equipped with a fuel cell stack according to an embodiment of the present invention.
  • FIG. 11 is a schematic diagram showing an outline of a measuring apparatus used for measuring contact resistance in Examples.
  • FIG. 12A is a graph showing the results of measurement of contact resistance before and after the immersion test for the conductive members produced in Examples I-1 to I-7 and Comparative Examples I-1 to I-5.
  • FIG. 12B is a graph showing the results of measurement of contact resistance before and after the immersion test for the conductive members produced in Example I-8 and Example I-9.
  • FIG. 13 is a schematic view showing a fuel cell stack to which a conductive member according to an embodiment of the present invention is applied.
  • 14 is a perspective view of the fuel cell stack of FIG. 15a and 15b are SEM photographs of the surfaces of Example I-9 and Example I-8. 16a and 16b are enlarged views of the SEM photographs of FIGS. 15a and 15b.
  • FIG. 17a and 17b are TEM photographs of the cross sections of Example I-9 and Example I-8.
  • 18a and 18b are SEM photographs observing the cross sections of Example I-9 and Example I-8.
  • FIG. 19 is a schematic plan view showing a manufacturing apparatus for forming an intermediate layer and a conductive carbon layer by sputtering.
  • FIG. 20 is a schematic plan view showing a manufacturing apparatus for forming an intermediate layer and a conductive carbon layer by an arc ion plating method.
  • FIG. 21 is a schematic cross-sectional view showing the configuration of the surface of the conductive member (separator) in the second embodiment.
  • FIG. 22A is a photograph showing the result of image analysis of the cross section of the dense barrier layer produced in Reference Example II-1 by TEM.
  • FIG. 22B is a photograph showing the result of image analysis of the cross section of the intermediate layer produced in Reference Example II-2 by TEM.
  • FIG. 23A is a photograph showing a result of image analysis of the surface of the dense barrier layer produced in Reference Example II-1 by SEM.
  • FIG. 23B is a photograph showing the result of image analysis performed on the surface of the intermediate layer prepared in Reference Example II-2 by SEM.
  • FIG. 23C is an SEM photograph showing the result of image analysis of the dense barrier layer produced in Reference Example II-1 in more detail than in FIG. 23A.
  • FIG. 23D is a SEM photograph showing the result of image analysis of the intermediate layer produced in Reference Example II-2 in more detail than FIG. 23B.
  • FIG. 23A is a photograph showing a result of image analysis of the surface of the dense barrier layer produced in Reference Example II-1 by SEM.
  • FIG. 24 is a photograph showing the result of image analysis of the cross section of the conductive member produced in Example II-2 by TEM.
  • FIG. 25 is a schematic cross-sectional view showing the configuration of the surface of the conductive member (separator) in the third embodiment.
  • FIG. 26 is a graph showing the measurement results of element concentration by Auger electron spectroscopy of a metal substrate (SUS316L) immersed in an aqueous sulfuric acid solution at 80 ° C. and pH 4 for 100 hours.
  • FIG. 27 is a graph showing the relationship between the coverage of conductive particles and contact resistance in a member in which conductive particles are coated on the surface of a metal substrate on which an oxide film is formed.
  • FIG. 28 is a cross-sectional view schematically showing a conductive member including conductive particles and a columnar material according to the third embodiment.
  • FIG. 29 is a drawing showing the element concentration profile in the stacking direction of the sample (III-1) measured by AES and before the endurance test.
  • FIG. 30 is a drawing showing the element concentration profile in the stacking direction of sample (III-1) after the endurance test, measured by AES.
  • FIG. 31 is a drawing showing the element concentration profile in the stacking direction of sample (III-2) after the endurance test, measured by AES.
  • FIG. 32 is a drawing showing the element concentration profile in the stacking direction of sample (III-3) after the endurance test, measured by AES.
  • FIG. 33 is a drawing showing the element concentration profile in the stacking direction of sample (III-4) after the endurance test, measured by AES.
  • FIG. 34 is a schematic cross-sectional view showing the configuration of the surface of the gas diffusion layer according to the fourth embodiment.
  • FIG. 35 is a schematic view microscopically showing the surface of the porous material layer.
  • FIG. 36 is a schematic view showing changes in fibers in each manufacturing process of PAN-based carbon fibers.
  • FIG. 37 is a schematic diagram showing an intermediate layer or conductive carbon layer deposition apparatus using a sputtering method.
  • FIG. 38 is a diagram showing a general PAN-based carbon fiber manufacturing process and a PAN-based carbon fiber manufacturing process in the fourth embodiment.
  • FIG. 39 is a diagram showing a method for measuring the contact resistance between the GDL obtained in Example IV-1 and Comparative Examples IV-1 and IV-2 and the separator.
  • FIG. 40 is a graph corresponding to the results regarding contact resistance of Example IV-1 shown in Table 5.
  • FIG. 41 is a graph showing the measurement result of the static contact angle of water with respect to the area ratio of conductive carbon and Au, calculated by AES surface mapping and image analysis.
  • FIG. 42 is a graph showing the resistance reduction effect when sputtering is performed while Au is dispersed on the surface of the conductive carbon layer.
  • FIG. 43 is a schematic cross-sectional view showing the configuration of the conductive member according to the fifth embodiment.
  • FIG. 44A is a cross-sectional view schematically showing a contact region between a gas diffusion base composed of carbon fibers or carbon particles and a conductive carbon layer in which conductive particles are dispersed.
  • FIG. 44B is a cross-sectional view schematically showing a contact region between a gas diffusion base composed of a porous metal and a conductive carbon layer in which conductive particles are dispersed.
  • FIG. 45 is a SEM photograph showing the surface of the conductive carbon layer in which conductive particles (Au) are dispersed in the separator (1).
  • FIG. 46 is an SEM photograph showing the surface of the conductive carbon layer in which conductive particles (Au) in the separator (2) are dispersed.
  • FIG. 47A is a drawing showing an element concentration profile in the stacking direction of the separator (2), measured by AES.
  • FIG. 47B is a drawing showing an element concentration profile in the stacking direction of the separator (4), measured by AES.
  • FIG. 48 is a graph showing the results of measurement of contact resistance for the separators produced in the examples and comparative examples.
  • FIG. 49 is a graph showing the results of measuring the contact angle for the separators produced in the examples and comparative examples.
  • the conductive member (conductive structure) of this embodiment has a metal base material and a conductive carbon layer containing conductive carbon located on at least one surface of the metal base material. And the intensity ratio R (I D / I G ) between the D band peak intensity (I D ) and the G band peak intensity (I G ) measured by the Raman scattering spectroscopic analysis of the conductive carbon layer is 1.3 or more. It is.
  • the conductive member of the present embodiment is preferably provided with a metal base and an intermediate layer on the metal base, and the conductive carbon layer is coated on the intermediate layer. And it is desirable for the said intermediate
  • the crystalline structure of the conductive carbon layer varies. Therefore, if the crystal structure of such a conductive carbon layer is different, the corrosion resistance and conductivity of the separator itself greatly vary due to this. In other words, it becomes difficult to stably control the fuel cell.
  • the metal separator provided by the prior art has sufficient corrosion resistance and conductivity that can withstand practical use even if it has been subjected to a surface treatment such as the arrangement of a conductive carbon layer. It could not be said that the sex was secured.
  • the crystal structure of the intermediate layer is controlled even if an intermediate layer such as a metal layer or its carbide layer is provided to ensure adhesion. There wasn't.
  • the anticorrosion function of the base material and the denseness of the conductive carbon film are insufficient, water molecules penetrate into the metal base material, and the corrosion resistance of the base material is promoted, resulting in an increase in contact resistance. It was.
  • positioned on the base-material surface itself is a layer with high insulation. For this reason, the problem that the electroconductivity of the thickness direction of a separator fell has arisen.
  • the columnar structure crystal of the intermediate layer is thickened as a measure for enhancing the anticorrosion function.
  • a metal base material such as aluminum, which is easily corroded
  • the columnar structure crystal of the intermediate layer is thickened as a measure for enhancing the anticorrosion function.
  • the present invention is an epoch-making thing that can reduce gaps and defects in the conductive carbon layer. Further, the protruding particles present in the outermost layer are caused by the development of the column diameter of the columnar structure of the intermediate layer, and the number of gaps in the outermost layer is reduced, and a function of suppressing water intrusion can be provided. . As a result, the anticorrosion effect of the metal substrate can be enhanced, and while being lightweight and inexpensive like aluminum, it can be stably applied as a separator substrate for a long time even in the case of a metal that is easily corroded.
  • the columnar structure of the intermediate layer is preferably a columnar crystal.
  • the columnar crystal that is the best as the columnar structure of the intermediate layer, but it is not necessarily limited to the columnar crystal and can be widely applied to the columnar structure. .
  • FIG. 1 is a cross-sectional view schematically showing a basic configuration of a fuel cell using a metal separator, which is an example of a conductive member of the present embodiment, specifically a basic configuration of a cell unit of a polymer electrolyte fuel cell (PEFC). is there.
  • FIG. 2 is a partial cross-sectional view showing an outline of a layer formed on the surface of the base material of the metal separator of FIG.
  • a solid polymer electrolyte membrane 2 and a pair of catalyst layers 3 sandwiching the solid polymer electrolyte membrane 2 on both sides thereof are provided.
  • the laminate of the solid polymer electrolyte membrane 2 and the catalyst layer 3 (3a, 3b) is further sandwiched between a pair of gas diffusion layers 4 (anode gas diffusion layer 4a and cathode gas diffusion layer 4b).
  • the solid polymer electrolyte membrane 2, the pair of catalyst layers (3a, 3b), and the pair of gas diffusion layers (4a, 4b) constitute a membrane electrode assembly (MEA) 9 in a stacked state.
  • the MEA 9 is further sandwiched by a pair of conductive metal separators 5 (an anode separator 5a and a cathode separator 5b) to constitute the cell unit 1.
  • the metal separators 5 a and 5 b are illustrated so as to be located on both sides of the MEA 9.
  • the metal separator 5 is generally used also as a metal separator 5 for an adjacent PEFC (see FIGS. 13 and 14).
  • the MEAs 9 are sequentially stacked via the metal separator 5 to constitute a stack.
  • a gas seal portion is disposed between the metal separators 5a and 5b and the solid polymer electrolyte membrane 2, or between the cell unit 1 and another cell unit 1 adjacent thereto.
  • these descriptions are omitted in FIGS. 1 and 2 (see FIGS. 13 and 14).
  • the metal separator 5 (5a, 5b) is obtained, for example, by forming a concavo-convex shape as shown in FIGS. 1, 2, and 13 by subjecting a thin plate having a thickness of 0.5 mm or less to a press treatment.
  • the convex part seen from the MEA 9 side of the metal separator 5 is in contact with the MEA 9. Thereby, the electrical connection with MEA9 is ensured.
  • a recess (a space between the metal separator 5 and the MEA 9 generated due to the uneven shape of the metal separator 5) as viewed from the MEA 9 side of the metal separator 5 is used to circulate gas during the operation of the PEFC 1. Functions as a gas flow path.
  • the fuel gas 5ag is circulated through the gas flow path 5aa of the anode separator 5a, and the oxidant gas 5bg is circulated through the gas flow path 5bb of the cathode separator 5b.
  • the fuel gas 5ag for example, hydrogen or a hydrogen-containing gas can be used
  • the oxidant gas 5bg for example, air or an O 2 -containing gas can be used.
  • the recess viewed from the side opposite to the MEA 9 side of the metal separator 5 serves as a refrigerant flow path 8 for circulating the refrigerant 8w for cooling the PEFC during operation of the PEFC 1.
  • the refrigerant 8w for example, cooling water or water can be used.
  • the metal separator 5 is usually provided with a manifold (not shown). This manifold functions as a connection means for connecting the cell units 1 when a stack is formed. With such a configuration, the mechanical strength of the fuel cell stack can be ensured (see FIGS. 13 and 14).
  • a gas seal is disposed between the metal separator 5 and the end of the electrolyte membrane 2 and between another cell unit 1 adjacent to the cell unit 1 of the fuel cell. Omitted.
  • the metal separator 5 has gas flow paths 5aa and 5bb that flow different fluids such as the fuel gas 5ag, the oxidant gas 5bg, and the refrigerant 8w, and the refrigerant flow.
  • a path 8 and a manifold are provided, and further, there is a function of maintaining the mechanical strength of the stack.
  • a perfluorosulfonic acid type membrane is usually used as the electrolyte membrane 2
  • the inside of the battery is weakly wet due to various acidic ions eluted from the electrolyte membrane and the humidified gas introduced into the battery. Under an acidic corrosive environment. For this reason, as shown in FIG.
  • the surface treatment of the metal separator 5 requires not only conductivity but also corrosion resistance.
  • the surface treatment layer 7 disposed on the metal substrate 6 of the metal separator 5 is essential to be applied to the reaction surface having severe corrosion conditions.
  • the reaction surface 7a is different from the cooling surface 7b. The same processing is required depending on the type and environment of the refrigerant (cooling water) 8w.
  • FIG. 3 is a cross-sectional view showing one form of the surface portion of the metal separator 5.
  • the conductive member constituting the metal separator 5 includes a metal base 31 and a conductive carbon layer 33. An intermediate layer 32 is interposed between them.
  • the metal separator 5 is arranged so that the conductive carbon layer 33 is located on the MEA 9 side.
  • FIG. 4A is a partial cross-sectional view showing the configuration and arrangement of each layer formed on the surface of the metal substrate of the metal separator, and is a simplified diagram for explaining functions required for each layer for surface treatment.
  • FIG. 4B is an enlarged view in which a part of FIG. 4A is enlarged to further clarify the configuration of an intermediate layer having a thick columnar crystal structure and a conductive carbon layer in which protruding particles are present on the outermost surface. is there.
  • FIG. 4C is an enlarged view that clarifies the configuration of the metal base material of the separator, the intermediate layer having a thin acicular crystal structure, and the conductive carbon layer having no protruding particles on the outermost surface.
  • the conductive members constituting the metal separator 5 are the metal base 31 (reference numeral 6 in FIG. 2) and the conductive carbon layer 33 (part of reference numeral 7 in FIG. 2: outer portion). And have. And between these, the intermediate
  • the metal separator 5 has a cross-sectional configuration in which an intermediate layer 32 and an outermost conductive carbon layer 33 are disposed on both main surfaces (surfaces) of the metal base 31 of the metal separator 5.
  • an intermediate layer 32 and an outermost conductive carbon layer 33 are disposed on both main surfaces (surfaces) of the metal base 31 of the metal separator 5.
  • the corrosion of the metal base material 31 of the metal separator 5 depends on the weak acid (acidity) in the battery and the surface potential of the metal separator 5. For this reason, when aluminum is used as the metal substrate 31 of the metal separator 5, it is necessary to prevent corrosion against acidity and potential. However, since the corrosion itself occurs for the first time due to the presence of water, a surface treatment in which the aluminum of the metal base 31 is not in contact with water as much as possible will take a countermeasure against the corrosion, and the effect is very great. For this reason, even if defects such as pinholes occur in the outermost conductive carbon layer 33, the penetration of water into the separator below the intermediate layer 32 is suppressed by controlling the crystal structure of the intermediate layer 32. Therefore, the expected excellent battery performance can be stably maintained for a long time.
  • each component of the metal separator 5 of this embodiment is explained in full detail.
  • the metal substrate 31 is a main layer of a conductive member that constitutes the metal separator 5, and contributes to ensuring conductivity and mechanical strength.
  • the constituent material of the metal substrate 31 examples include iron, titanium, copper, aluminum, and alloys thereof. These materials are preferably used from the viewpoints of mechanical strength, versatility, cost performance, or processability.
  • the iron alloy includes stainless steel.
  • the metal base material 31 is comprised from stainless steel, aluminum, or aluminum alloy.
  • the GDL is composed of a portion where the surface pressure is directly applied to the GDL 4 (4a, 4b) (the metal separator 5 and the contact portion; a rib portion) and a portion that is not directly applied (the portion that is not in contact; the flow path portion).
  • the rib shoulder portion refers to the shoulder portion of the contact portion with the metal separator 5.
  • Examples of stainless steel include austenite, martensite, ferrite, austenite / ferrite, and precipitation hardening.
  • austenite include SUS201, SUS202, SUS301, SUS302, SUS303, SUS304, SUS305, SUS316 (L), and SUS317, which are defined in Japanese Industrial Standards.
  • Examples of the austenite-ferrite type include SUS329J1.
  • Examples of the martensite system include SUS403 and SUS420.
  • Examples of the ferrite type include SUS405, SUS430, and SUS430LX.
  • the precipitation hardening system include SUS630.
  • austenitic stainless steel such as SUS304 and SUS316.
  • the content of iron in the stainless steel is preferably 60 to 84% by mass, more preferably 65 to 72% by mass.
  • the chromium content in the stainless steel is preferably 16 to 20% by mass, more preferably 16 to 18% by mass.
  • examples of the aluminum alloy include pure aluminum, aluminum / manganese, and aluminum / magnesium.
  • the elements other than aluminum in the aluminum alloy are not particularly limited as long as they are generally usable as an aluminum alloy.
  • copper, manganese, silicon, magnesium, zinc and nickel are included in the aluminum alloy.
  • Specific examples of the aluminum alloy include A1050 and A1050P specified in Japanese Industrial Standards as pure aluminum, A3003P and A3004P as aluminum / manganese, and A5052P and A5083P as aluminum / magnesium. Can be mentioned.
  • the separator is also required to have mechanical strength and formability, the alloy tempering is appropriately selected in addition to the above alloy types.
  • the metal base material 31 is comprised from the simple substance of titanium or aluminum, the purity of the said titanium or aluminum becomes like this. Preferably it is 95 mass% or more, More preferably, it is 97 mass% or more, More preferably, it is 99 mass % Or more.
  • the thickness of the metal substrate 31 is preferably 50 ⁇ m to 500 ⁇ m from the viewpoint of ease of processing and mechanical strength, and improvement of the energy density of the battery by making the separator 5 itself a thin film.
  • the thickness of the metal substrate is more preferably 80 ⁇ m to 300 ⁇ m, still more preferably 80 ⁇ m to 200 ⁇ m.
  • the thickness of the metal substrate 31 when stainless steel is used is preferably 80 ⁇ m to 150 ⁇ m.
  • the thickness of the metal substrate 31 when aluminum is used is preferably 100 ⁇ m to 300 ⁇ m. When it is within the above range, the metal separator 5 has sufficient strength, but is excellent in workability and can achieve a suitable thickness.
  • the metal base 31 is preferably made of a material having a high gas barrier property. Since the separator 5 of the fuel cell plays a role of partitioning cells, different gas flows on both sides of the separator 5 (see FIG. 13). Therefore, from the viewpoint of eliminating the mixing of adjacent gases and the fluctuation of the gas flow rate, the metal base 31 is preferably as the gas barrier property is higher.
  • the conductive carbon layer 33 is a layer containing conductive carbon. The presence of this layer improves the corrosion resistance as compared with the case of only the metal substrate 31 while ensuring the conductivity of the conductive member constituting the metal separator 5.
  • the conductive carbon layer 33 has an intensity ratio R (I D / I G ) between the D band peak intensity (I D ) and the G band peak intensity (I G ) measured by Raman scattering spectroscopy. It is prescribed by. Specifically, the intensity ratio R (I D / I G ) is 1.3 or more.
  • R (I D / I G ) is 1.3 or more.
  • the intensity ratio R (I D / I G ) between the D band peak intensity (I D ) and the G band peak intensity (I G ) is the graphite cluster size of the carbon material and the disorder of the graphite structure (crystal structure defect), Used as an index such as sp 2 bond ratio. That is, in the present embodiment, the R value can be used as an index of the contact resistance of the conductive carbon layer 33 and can be used as a film quality parameter for controlling the conductivity of the conductive carbon layer 33.
  • the R (I D / I G ) value is calculated by measuring the Raman spectrum of the carbon material using a microscopic Raman spectrometer. Specifically, the peak intensity of 1300 ⁇ 1400 cm -1 called the D band (I D), the relative intensity ratio of the peak intensity of 1500 ⁇ 1600 cm -1 called the G band (I G) (peak area ratio ( I D / I G )).
  • the R value is 1.3 or more.
  • the R value is preferably 1.4 to 2.0, more preferably 1.4 to 1.9, and further preferably 1.5 to 1.8. If the R value is 1.3 or more, the conductive carbon layer 33 in which the conductivity in the stacking direction of the fuel cell is sufficiently secured can be obtained. Moreover, if R value is 2.0 or less, the reduction
  • increasing the D-band peak intensity means an increase in crystal structure defects in the graphite structure.
  • the conductive member A and the conductive member B use SUS316L as the metal base 31 and have an intermediate layer 32 (thickness: 0.2 ⁇ m) made of Cr and a conductive carbon layer 33 (thickness) on the surface. : 0.2 ⁇ m) was sequentially formed by a sputtering method. Further, the bias voltage applied to the metal base material 31 when the conductive carbon layer 33 in the conductive member A is manufactured is 0 V, and the metal base material 31 is applied when the conductive carbon layer 33 in the conductive member B is manufactured. The applied bias voltage was -140V.
  • the conductive carbon layer of the conductive member B has a structure of polycrystalline graphite. That is, it can be seen that there are many graphite clusters 33c. On the other hand, such a structure of polycrystalline graphite cannot be confirmed in the conductive carbon layer of the conductive member A shown in FIG. 5A.
  • polycrystalline graphite microscopically has an anisotropic graphite crystal structure (graphite cluster) in which graphene surfaces (hexagonal network surfaces) are laminated, but macroscopically, a large number of such graphite structures. Is an isotropic crystal. Accordingly, it can be said that polycrystalline graphite is a kind of diamond-like carbon (DLC). Normally, single crystal graphite has a disordered structure in which graphene surfaces are laminated even when viewed macroscopically, as represented by HOPG (highly oriented pyrolytic graphite). On the other hand, in polycrystalline graphite, a graphite structure exists as an individual cluster, and has a turbostratic structure.
  • HOPG highly oriented pyrolytic graphite
  • this degree of disorder (graphite cluster amount, size) is appropriately ensured, and a conductive path from one surface of the conductive carbon layer 33 to the other surface is ensured.
  • a decrease in conductivity due to the separate provision of the conductive carbon layer 33 in addition to the metal substrate 31 is prevented.
  • an intermediate layer 32 is provided between the metal substrate 31 and the conductive carbon layer 33, and further, the crystal structure is controlled, thereby sufficiently ensuring excellent conductivity. An increase in contact resistance can be suppressed.
  • polycrystalline graphite since the graphene surface is formed by the bonding of sp 2 carbon atoms constituting the graphite cluster, conductivity is ensured in the plane direction of the graphene surface.
  • Polycrystalline graphite is substantially composed of only carbon atoms, has a small specific surface area, and a small amount of bonded functional groups. For this reason, polycrystalline graphite has excellent resistance to corrosion by acidic water or the like.
  • primary particles are often formed by aggregates of graphite clusters, thereby exhibiting electrical conductivity.
  • the individual particles are separated, there are many functional groups formed on the surface, and corrosion due to acidic water or the like is likely to occur. Further, even when the conductive carbon layer 33 is formed with carbon black, there is a problem that the denseness as a protective film is lacking.
  • the size of the graphite cluster constituting the polycrystalline graphite is not particularly limited.
  • the average diameter of the graphite cluster is preferably about 1 nm to 50 nm, more preferably 2 nm to 10 nm.
  • the “diameter” of the graphite cluster means the maximum distance among the distances between any two points on the contour line of the cluster.
  • the average diameter value of the graphite clusters is calculated as an average value of the diameters of the clusters observed in several to several tens of fields using an observation means such as SEM or TEM.
  • a part of the conductive carbon layer 33 is formed on the surface of the intermediate layer 32, and has protruding particles 33a having a diameter of 200 nm to 500 nm. desirable. More preferably, it is particularly desirable that protruding particles 33a having a diameter of 200 nm to 500 nm and fine particles 33b of 50 nm to 100 nm are mixed on the outermost surface of the conductive member (see Example I-8). However, in this embodiment, as shown in FIG. 4C, the protruding particles 33a having a diameter of 200 nm to 500 nm may not be provided on the outermost surface of the conductive member.
  • the conductive carbon layer 33 is composed of only fine particles 33b of 50 nm to 100 nm. Also good. Even in such a configuration, if the strength ratio R of the conductive carbon layer 33 is 1.3 or more, the intended object of the present invention can be achieved (see Example I-9).
  • an intermediate layer 32 is provided between the conductive carbon layer 33 and the metal substrate 31, the crystal structure of the intermediate layer 32 is controlled, and the column diameter of the columnar crystal is set to the conductive carbon layer 33.
  • the protruding particles 33a having a diameter of 200 nm to 500 nm, preferably 300 nm to 500 nm, more preferably 400 nm to 500 nm are present on the outermost surface, the number of gaps on the outermost surface of the conductive member is reduced and water enters. Can be suppressed.
  • the fine particles 33b are present in the peripheral portion other than the protruding particles 33a (a flat portion having a small unevenness change amount), it is particularly effective in reducing gaps and defects in the conductive carbon layer 33. .
  • the anticorrosion effect of the metal substrate 31 can be enhanced, and even a metal that is easily corroded such as aluminum can be applied as the metal substrate 31.
  • the diameter of the protruding particle 33a on the outermost surface of the conductive member is measured by using observation means such as a scanning electron microscope (SEM) or a transmission electron microscope (TEM). It is calculated as an average value of the diameters.
  • the size (diameter) of the fine particles 33b on the outermost surface of the conductive member also refers to the range of the particle size distribution.
  • the size of the fine particles 33b on the outermost surface of the conductive member can also be measured in the same manner as the protruding particles 33a.
  • the particle diameter of the protruding particles 33a can be determined by measuring the maximum length of thin (white) particles having a low contrast from the observation result of the sample surface by SEM.
  • the protruding particles 33a be present in the range of at least 30 or more, preferably 30 to 100, more preferably 50 to 80 per 100 ⁇ m 2 .
  • the gap in the intermediate layer 32 is reduced, formation of an oxide film inside the surface treatment can be suppressed, and an increase in contact resistance can be suppressed.
  • the number of the projecting particles 33a is less than 30 per 100 ⁇ m 2 , since the development of the columnar crystal diameter of the intermediate layer 32 is reduced, the number of gaps between the columnar crystals on the outermost surface of the conductive member is reduced. This may increase the contact resistance.
  • the present invention even if the number of the protruding particles 33a per 100 ⁇ m 2 is less than 30, even if it is within the range not impairing the effect of the present embodiment, it is included in the present invention. .
  • the conductivity from one surface of the conductive carbon layer 33 to the other surface is controlled. Since the path is secured, a conductive member having sufficiently improved corrosion resistance while sufficiently securing excellent conductivity is provided (FIGS. 4C, 15A, 16A, 17A, 18A, Example I- 9).
  • the distance between the vertices of the outermost protruding particles 33a is preferably within 1 ⁇ m (see FIG. 4B).
  • the height H of the protruding particles 33a is 100 nm to 500 nm, preferably 200 nm to 500 nm, more preferably 300 nm to 400 nm with respect to the peripheral portion (see FIG. 4B). .
  • the height H of the protruding particles 33a is within the above range, the columnar crystal of the intermediate layer 32 grows and the column diameter W of the intermediate layer is increased, so that the gap in the intermediate layer is further reduced. Further, the anticorrosion function of the metal substrate 31 can be further improved.
  • the conductive member has a protruding shape in which the protruding particles 33a are present on the outermost surface, the specific surface area is improved.
  • the protruding particles 33a are particles that constitute a part of the conductive carbon layer, and further protrude along the protrusions of the intermediate layer.
  • the fine particles 33b are particles that constitute a part of the conductive carbon layer but do not protrude as compared with the protruding particles.
  • grain can be picked up from the contrast confirmed from the surface observation by SEM, and it can obtain
  • the height H (H 1 , H 2 , H 3 ) of the protruding particle 33a is the height from the surface of the microparticle 33b existing around the protruding particle 33a to the tip of the protruding particle 33a.
  • the height of the protruding particles 33a can be obtained by cross-sectional observation with a TEM.
  • the method for measuring the number of protruding particles 33a having a diameter of 200 to 500 nm per 100 ⁇ m 2 is performed as follows. First, the particle-like thing confirmed as white as contrast by surface observation by SEM is caught as a protruding particle. Next, the number of particles having the above particle diameter present in 100 ⁇ m 2 is measured. (D) Regarding the method for measuring the microparticles 33b having a diameter of 50 to 100 nm, the particles having the above particle diameter can be measured by surface observation with an SEM.
  • the conductive carbon layer 33 may be substantially composed only of polycrystalline graphite or may be composed only of polycrystalline graphite, but the conductive carbon layer 33 is other than polycrystalline graphite.
  • Other materials may also be included.
  • the carbon material other than the polycrystalline graphite include graphite block (highly crystalline graphite), carbon black, fullerene, carbon nanotube, carbon nanofiber, carbon nanohorn, and carbon fibril.
  • Specific examples of carbon black include ketjen black, acetylene black, channel black, lamp black, oil furnace black, or thermal black. Carbon black may be subjected to a graphitization treatment. These carbon materials may be used in combination with a resin such as a polyester resin, an aramid resin, or a polypropylene resin.
  • gold As a material other than the carbon material included in the conductive carbon layer 33, gold (Au), silver (Ag), platinum (Pt), ruthenium (Ru), palladium (Pd), rhodium (Rh), indium ( A noble metal such as In); a water repellent material such as polytetrafluoroethylene (PTFE); and a conductive oxide.
  • gold Au
  • silver Ag
  • platinum Pt
  • Ru palladium
  • Rhodium Rh
  • indium A noble metal such as In
  • a water repellent material such as polytetrafluoroethylene (PTFE); and a conductive oxide.
  • PTFE polytetrafluoroethylene
  • conductive oxide As for materials other than polycrystalline graphite, only 1 type may be used and 2 or more types may be used together.
  • the average particle size when the carbon material other than the polycrystalline graphite is in the form of particles is preferably 2 nm to 100 nm, more preferably 5 nm to 20 nm, from the viewpoint of suppressing the thickness of the conductive carbon layer.
  • the “particle diameter” means the maximum distance among the distances between any two points on the particle outline.
  • the value of “average particle size” is a value calculated as an average value of the particle size of particles observed in several to several tens of fields using an observation means such as SEM or TEM unless otherwise specified. Shall be adopted.
  • the diameter is preferably 0.4 nm to 100 nm, more preferably 1 nm to 20 nm.
  • the length in the case of the fibrous form is 5 nm to 200 nm, more preferably 10 nm to 100 nm.
  • the aspect ratio in the case of the fibrous form is 1 to 500, more preferably 2 to 100.
  • the average thickness of the conductive carbon layer 33 excluding the protruding particles 33a is preferably 1 nm to 1000 nm, more preferably 2 nm to 500 nm, and further preferably 5 nm to 200 nm.
  • the thickness of the conductive carbon layer 33 is a value within such a range, sufficient conductivity can be ensured between the gas diffusion base and the metal separator 5.
  • the metal base 31 can have a high corrosion resistance function.
  • the conductive carbon layer 33 may be present only on one surface of the conductive member (metal separator 5) as shown in FIG. 3, but preferably shown in FIG. 2, FIG. 4A, and the like. Thus, it is desirable that the conductive carbon layers 33 exist on both surfaces of the conductive member. This is because the anticorrosion effect of the metal substrate 31 can be further maintained while securing the adhesion between the metal substrate 31 and the conductive carbon layer 33 via the intermediate layer 32 on both surfaces of the conductive member. .
  • the average peak measured by the rotational anisotropy measurement of the Raman scattering spectroscopic analysis shows a two-fold symmetry pattern.
  • the measurement principle of rotational anisotropy measurement will be briefly described.
  • Rotational anisotropy measurement of Raman scattering spectroscopic analysis is performed by performing Raman scattering spectroscopic measurement while rotating the measurement sample 360 degrees in the horizontal direction. Specifically, the surface of the measurement sample is irradiated with laser light, and a normal Raman spectrum is measured. Next, the measurement sample is rotated by 10 °, and the Raman spectrum is measured in the same manner. This operation is performed until the measurement sample rotates 360 °. And the average peak is obtained by calculating the average value of the peak intensities obtained at the respective angles, and displaying the weakest of the measured peak intensities as the center O and displaying the polar coordinates at 360 ° per revolution. .
  • FIG. 6A when the graphite layer is present on the sample surface so that the graphene surface is parallel to the surface direction of the sample, a three-fold symmetry pattern as shown in FIG. 6A can be seen.
  • FIG. 6B when the graphite layer is present on the sample surface so that the graphene surface is perpendicular to the surface direction of the sample, a two-fold symmetry pattern as shown in FIG. 6B can be seen.
  • FIG. 6C When an amorphous carbon layer having no clear crystal structure is present on the sample surface, a pattern not showing symmetry as shown in FIG. 6C can be seen.
  • the conductivity in the conductive carbon layer 33 is ensured by the shortest path, which is preferable.
  • FIGS. 7A and 7B show the results of the rotational anisotropy measurement described above.
  • FIG. 7A shows a Raman spectrum when the conductive member B is used as a measurement sample and the rotation angles of the sample are 0 °, 60 °, and 180 °, respectively.
  • FIG. 7B shows an average peak of rotational anisotropy measurement for the conductive member B obtained by the above-described method. As shown in FIG. 7B, in the measurement of rotational anisotropy of the conductive member B, peaks were observed at 0 ° and 180 ° positions. This corresponds to the two-fold symmetry pattern shown in FIG. 6B. In this specification, “showing a two-fold symmetry pattern” means that, as shown in FIG.
  • the Vickers hardness of the conductive carbon layer 33 is defined.
  • “Vickers hardness (Hv)” is a value that defines the hardness of a substance, and is a value inherent to the substance.
  • the Vickers hardness means a value measured by a nanoindentation method.
  • the nanoindentation method is a method in which the diamond indenter is continuously loaded and unloaded with a very small load on the sample surface, and the hardness is measured from the obtained load-displacement curve. Larger means that the substance is harder.
  • the Vickers hardness of the conductive carbon layer 33 is preferably 1500 Hv or less, more preferably 1200 Hv or less, further preferably 1000 Hv or less, and particularly preferably 800 Hv or less. .
  • the Vickers hardness is a value within such a range, excessive mixing of sp 3 carbon having no conductivity is suppressed, and a decrease in the conductivity of the conductive carbon layer 33 can be prevented.
  • the lower limit value of the Vickers hardness is not particularly limited, but if the Vickers hardness is 50 Hv or more, the hardness of the conductive carbon layer 33 is sufficiently ensured.
  • the conductive member (separator 5) that can withstand impacts such as external contact and friction, and has excellent adhesion to the metal substrate 31 as a base.
  • the intermediate layer 32 is provided as in the present embodiment, it is possible to provide a conductive member that is more excellent in adhesion than the conductive carbon layer 33 and the intermediate layer 32 and further the metal base 31. it can.
  • the Vickers hardness of the conductive carbon layer 33 is more preferably 80 Hv or more, further preferably 100 Hv or more, and particularly preferably 200 Hv or more.
  • SUS316L is prepared as the metal base 31 of the conductive member.
  • an intermediate layer 32 (thickness 0.2 ⁇ m) made of Cr and a conductive carbon layer 33 (thickness 0.2 ⁇ m) were sequentially formed by sputtering.
  • the average value of the columnar crystal column thickness in the cross section of the intermediate layer 32 is 200 nm to 500 nm, and the columnar crystal having this thickness is electrically conductive in the entire intermediate layer 32. 60% of the total thickness of the intermediate layer is present on the carbonaceous carbon layer 33 side.
  • the conductive carbon layer 33 has a mixture of protruding particles 33a having a diameter (particle size distribution) of 200 nm to 500 nm and fine particles 33b of 50 nm to 100 nm on the outermost surface, and the protruding particles 33a are mixed. There are 60 on average per 100 ⁇ m 2 .
  • the crystal structure of the intermediate layer 32 is controlled to create a columnar crystal diameter having a desired column diameter and number, and then the Vickers hardness of the conductive carbon layer 33. Changed.
  • FIG. 8 shows the relationship between the Vickers hardness of the conductive carbon layer 33 and the value of the sp 3 ratio in the conductive member thus obtained.
  • FIG. 8 shows the relationship between the Vickers hardness of the conductive carbon layer 33 and the value of the sp 3 ratio in the conductive member thus obtained.
  • the amount of hydrogen atoms contained in the conductive carbon layer 33 it is preferable to consider the amount of hydrogen atoms contained in the conductive carbon layer 33. That is, when the conductive carbon layer 33 includes a hydrogen atom, the hydrogen atom is bonded to the carbon atom. Then, the hybrid orbital of the carbon atom to which the hydrogen atom is bonded is changed from sp 2 to sp 3 and the conductivity is lost, and the conductivity of the conductive carbon layer 33 is lowered. Further, when the C—H bond in the polycrystalline graphite is increased, the continuity of the bond is lost, the hardness of the conductive carbon layer 33 is lowered, and finally the mechanical strength and corrosion resistance of the conductive member are lowered. .
  • the content of hydrogen atoms in the conductive carbon layer 33 is preferably 30 atomic percent or less, more preferably 20 atomic percent or less, with respect to all atoms constituting the conductive carbon layer 33. More preferably, it is 10 atomic% or less.
  • a value obtained by elastic recoil scattering analysis (ERDA) is adopted as the value of the hydrogen atom content in the conductive carbon layer 33. In this method, a measurement sample is tilted, and a helium ion beam is incident shallowly, thereby detecting an element ejected forward. Since the nucleus of a hydrogen atom is lighter than the incident helium ion, if a hydrogen atom is present, the nucleus is ejected forward.
  • the energy spectrum of the ejected atom reflects the mass of the nucleus. Therefore, the content of hydrogen atoms in the measurement sample is measured by measuring the number of nuclei of the ejected hydrogen atoms with a solid detector.
  • FIG. 9 is a graph showing the results of measuring the contact resistance of several conductive members having the conductive carbon layer 33 having the above-described R value of 1.3 or more but having different hydrogen atom contents. It is. As shown in FIG. 9, when the content of hydrogen atoms in the conductive carbon layer 33 is 30 atomic% or less, the value of the contact resistance of the conductive member is significantly reduced.
  • SUS316L was used as the metal base 31 of the conductive member.
  • An intermediate layer 32 (thickness 0.2 ⁇ m) made of Cr and a conductive carbon layer 33 (thickness 0.2 ⁇ m) were sequentially formed on the surface by sputtering. At this time, the hydrogen atom content in the conductive carbon layer was changed by controlling the film formation method and the amount of hydrocarbon gas.
  • the entire metal base 31 is covered with the conductive carbon layer 33 through the intermediate layer 32.
  • the ratio (coverage) of the area where the metal base 31 is covered with the conductive carbon layer 33 is 100%.
  • a coverage may be less than 100%.
  • the coverage of the metal substrate 31 by the conductive carbon layer 33 is preferably 50% or more, more preferably 80% or more, still more preferably 90% or more, and most preferably 100%.
  • the coverage is determined by viewing the conductive member (metal separator 5) from the stacking direction.
  • the ratio of the area of the metal substrate 31 overlapping with the conductive carbon layer 33 is meant.
  • the conductive member constituting the metal separator 5 has an intermediate layer 32.
  • the intermediate layer 32 has a function of improving the adhesion between the metal substrate 31 and the conductive carbon layer 33 and a function of preventing elution of ions from the metal substrate 31.
  • the R value exceeds the upper limit of the preferable range described above, the effect of providing the intermediate layer 32 is remarkably exhibited.
  • the intermediate layer 32 is provided even when the R value is included in the preferred range described above. From another point of view, the above-described operation and effect due to the installation of the intermediate layer 32 are more prominently exhibited when the metal substrate 31 is made of aluminum or an alloy thereof.
  • middle layer 32 is demonstrated.
  • the columnar crystal structure refers to a structure in which the crystals constituting the intermediate layer grow in a columnar shape in the film thickness direction.
  • (B) The method for measuring the average value of the column thickness W of the columnar crystals in the cross section of the intermediate layer is determined as follows. First, from a cross-sectional observation result by TEM, for a columnar crystal growing in a direction perpendicular to the metal substrate 31, one column is specified from the interface of the column confirmed by contrast, and is parallel to the metal substrate. It can be obtained by calculating the distance from one interface in the direction to the other interface.
  • the thickness of the columnar crystal column in the cross section of the intermediate layer is 200 to 500 nm, and the columnar crystal having the thickness of the intermediate layer has the entire intermediate layer thickness on the conductive carbon layer side of the entire intermediate layer.
  • the percentage is calculated as follows. As shown in FIG. 4B, the ratio (T 2 / T 1 ) of the thickness T 2 of the columnar crystal having the above thickness with respect to the average thickness T 1 of the intermediate layer is obtained from the cross-sectional observation result by TEM.
  • the thickness T 1 of the intermediate layer the thickness excluding the height H 4 of the projections 32a in the intermediate layer.
  • the conductive carbon layer side in the entire intermediate layer refers to a 50% region on the conductive carbon layer side in the thickness direction of the intermediate layer.
  • the measuring method of the film thickness (average value) of the intermediate layer can be read from the cross-sectional observation result by SEM or TEM.
  • the intermediate layer 32 has a columnar crystal structure. And although mentioned later for details, it is desirable to form the intermediate
  • the intermediate layer 32 is provided between the conductive carbon layer 33 and the metal substrate 31, the columnar crystal structure of the intermediate layer 32 is controlled, and the column diameter of the columnar crystal is set to be conductive.
  • columnar protrusions (convex portions) are formed on the surface of the intermediate layer 32.
  • the conductive carbon layer 33 thereon the conductive carbon layer 33 is formed along the undulations on the surface of the intermediate layer 32.
  • a conductive member having a structure in which the intermediate layer 32 has a columnar crystal structure and the protruding particles 33a exist on the outermost surface of the conductive member is provided.
  • the gap between the columnar crystals of the intermediate layer 32 and the conductive carbon present thereon are formed.
  • the gaps and defects in the layer 33 are greatly reduced. That is, the protruding particles 33a are due to the development of the columnar diameter of the intermediate layer 32, and the number of outermost layer gaps can be reduced to provide a function of suppressing water intrusion.
  • a material that imparts the above-mentioned adhesion is preferable.
  • Group 4 metals Ti, Zr, Hf
  • Group 5 metals V, Nb, Ta
  • Group 6 metals Cr, Mo, W
  • their carbides nitriding And carbonitrides.
  • metals with low ion elution such as chromium (Cr), tungsten (W), titanium (Ti), molybdenum (Mo), niobium (Nb) or hafnium (Hf), or their nitrides, carbides or charcoal are preferable.
  • Nitride is used.
  • Cr or Ti or a carbide or nitride thereof is used.
  • the role of the intermediate layer 32 is to ensure adhesion with the upper conductive carbon layer 33 and to prevent corrosion of the underlying metal substrate 31.
  • the metal substrate 31 made of aluminum or an alloy thereof corrosion proceeds due to moisture reaching the vicinity of the interface, and an aluminum oxide film is formed. As a result, the conductivity in the film thickness direction of the entire metal base 31 is deteriorated.
  • Chromium and titanium are particularly useful in that, due to the formation of a passive film, even if exposed portions are present, their own elution is hardly observed.
  • the metal especially Cr or Ti
  • the average value of the columnar crystal column thicknesses W 1 , W 2 , W 3 in the cross section of the intermediate layer 32 is 200 nm to 500 nm, preferably 300 nm to 500 nm, more preferably 400 nm to 500 nm. It is desirable that By having the columnar crystals having a thickness within such a range that the average column thickness of the columnar crystals in the cross section of the intermediate layer 32 is present, the amount of gaps between the columnar crystals is reduced, and the penetration of moisture reaching the metal substrate 31 Can be suppressed.
  • the intermediate layer 32 When providing the intermediate layer 32, it is preferable to control the crystal structure of the intermediate layer 32 so that the column diameter of the columnar crystals of the intermediate layer 32 is increased to the interface with the conductive carbon layer 33. Thereby, the clearance gap and defect in the conductive carbon layer 33 formed on it can be remarkably reduced.
  • the particle diameter of the protruding particles 33a in the outermost layer of the conductive member (metal separator 5) is closely related to the column diameter of the columnar crystals. And when the column diameter of the columnar crystal is increased and the particle diameter of the protruding particles 33a is 200 nm to 500 nm, the number of gaps in the outermost layer of the conductive member is reduced, and the function of suppressing water intrusion is achieved. Can be granted.
  • the thickness of the columnar crystal column in the cross section is preferably 200 nm to 500 nm. Further, regarding the columnar crystal having the thickness, 5 to 95% of the total thickness of the intermediate layer 32 is constituted by the columnar crystal having the thickness, and the columnar crystal having the thickness is further on the conductive carbon layer 33 side. It is desirable to exist. In the present embodiment, it is desirable that the thickness of the columnar crystal on the outermost surface of the intermediate layer 32 is maintained up to the interface between the metal base 31 and the intermediate layer 32 as much as possible. However, when the intermediate layer 32 is first formed on the metal substrate 31, it is necessary to increase the energy applied to the surface in order to thicken the columnar crystals from the beginning.
  • the thickness of the columnar crystal on the metal substrate 31 side is preferably thinner than that on the conductive carbon layer 33 side.
  • the anticorrosion effect of the metal substrate 31 can be maintained more stably while ensuring the adhesion between the metal substrate 31 and the conductive carbon layer 33.
  • the columnar crystal column thickness in the cross section is 200 to 500 nm, preferably 200 to 400 nm, and more preferably 200 to 300 nm.
  • the columnar crystals having the above thickness are present in an amount of 5 to 95%, preferably 20 to 90%, more preferably 50 to 90% of the entire thickness of the intermediate layer 32, and the columnar crystals having the above thickness are further conductive. It is preferably formed on the side of the carbonaceous layer 33.
  • the thickness of the intermediate layer 32 is not particularly limited. However, from the viewpoint of making the size of the fuel cell stack as small as possible by making the metal separator 5 thinner, the thickness of the intermediate layer 32 is preferably 0.01 ⁇ m to 10 ⁇ m, more preferably 0.02 ⁇ m. Is 5 ⁇ m, more preferably 0.05 ⁇ m to 5 ⁇ m, and particularly preferably 0.1 ⁇ m to 1 ⁇ m. If the thickness of the intermediate layer 32 is 0.01 ⁇ m or more, a uniform layer is formed, and the corrosion resistance of the metal substrate 31 can be effectively improved.
  • the thickness of the intermediate layer 32 is 10 ⁇ m or less, an increase in the film stress of the intermediate layer 32 is suppressed, and a decrease in film followability to the metal substrate 31 and occurrence of peeling / cracking associated therewith are prevented. .
  • the thickness of the intermediate layer 32 is 0.02 ⁇ m to 5 ⁇ m.
  • the intermediate layer 32 has a film thickness within the above range, it is more desirable to have the following configuration. That is, columnar crystals having a thickness of 200 nm to 500 nm on the surface of the intermediate layer 32 on the side of the conductive carbon layer 33 are the entire thickness of the intermediate layer 32 with respect to the direction from the conductive carbon layer 33 to the metal substrate 31. It is desirable to maintain at 5% or more.
  • the columnar crystals having the above thickness are preferably in the range of 20 to 90%, more preferably 50 to 90% of the entire thickness of the intermediate layer 32 with respect to the direction from the conductive carbon layer 33 to the metal substrate 31. It is desirable that it be maintained.
  • the film thickness of the intermediate layer 32 is less than 0.02 ⁇ m, the columnar crystal structure of the intermediate layer 32 is undeveloped, and it is difficult to maintain the denseness.
  • the film thickness of the intermediate layer 32 exceeds 5 ⁇ m, the film stress increases and the adhesiveness with the metal substrate 31 is deteriorated, so that cracks and peeling may occur.
  • the thickness of the intermediate layer 32 may be increased to about 10 ⁇ m as long as the intended effect of the present invention is not impaired.
  • the intermediate layer 32 has such a three-dimensional structure, the anticorrosion effect of the metal substrate 31 can be maintained more stably while strengthening the adhesion between the metal substrate 31 and the conductive carbon layer 33.
  • the surface of the intermediate layer 32 on the side of the conductive carbon layer 33 is preferably formed with irregularities at the nano level. According to such a form, the adhesion of the conductive carbon layer 33 to the intermediate layer 32 is further improved.
  • the thermal expansion coefficient of the intermediate layer 32 is a value close to the thermal expansion coefficient of the metal constituting the metal substrate 31, the adhesion between the intermediate layer 32 and the metal substrate 31 is improved. However, in such a form, the adhesion between the intermediate layer 32 and the conductive carbon layer 33 may be reduced. Similarly, when the thermal expansion coefficient of the intermediate layer 32 is close to the thermal expansion coefficient of the conductive carbon layer 33, the adhesion between the intermediate layer 32 and the metal substrate 31 may be lowered.
  • the thermal expansion coefficient ( ⁇ mid ) of the intermediate layer 32, the thermal expansion coefficient ( ⁇ sub ) of the metal base 31, and the thermal expansion coefficient ( ⁇ c ) of the conductive carbon layer 33 are expressed by the following relationship: Is preferably satisfied.
  • the intermediate layer 32 only needs to be present on at least one surface of the metal substrate 31, and is desirably present on both surfaces of the metal substrate 31.
  • the conductive carbon layer 33 may be present on both surfaces of the metal base 31.
  • the intermediate layer 32 is preferably interposed between the metal base 31 and both conductive carbon layers 33, respectively.
  • the intermediate layer 32 is disposed on the MEA 9 side. It is preferable that it exists in.
  • an aluminum plate having a desired thickness, an alloy plate thereof, a titanium plate, a stainless steel plate, or the like is prepared.
  • the surface of the constituent material of the prepared metal base 31 is degreased and cleaned using an appropriate solvent.
  • the solvent ethanol, ether, acetone, isopropyl alcohol, trichloroethylene, a caustic agent, or the like can be used.
  • the degreasing and cleaning treatment include ultrasonic cleaning.
  • the ultrasonic cleaning conditions are a processing time of about 1 to 10 minutes, a frequency of about 30 to 50 kHz, and a power of about 30 to 50 W.
  • the oxide film formed on the surface of the constituent material of the metal base 31 is removed.
  • the method for removing the oxide film include a cleaning treatment with an acid, a dissolution treatment by applying a potential, or an ion bombardment treatment.
  • a method in which alkali immersion cleaning, removal of an oxide film with alkali (alkali etching), surface activation with a hydrofluoric acid mixed acid solution, and subsequent zincate treatment in a zinc substitution bath is preferably used.
  • the conditions for the zincate treatment are not particularly limited.
  • the bath temperature is 10 to 40 ° C. and the immersion time is 20 to 90 seconds. Note that the oxide film removing step may be omitted.
  • the treatment is preferably performed on at least the surface of the metal plate on which the intermediate layer is formed, but more preferably on both surfaces of the metal plate.
  • a conductive carbon layer 33 is formed on the surface of the constituent material of the metal base 31 subjected to the above-described treatment.
  • the conductive carbon layer 33 is formed by laminating a layer containing conductive carbon on the metal substrate 31 at the atomic level using the constituent material (for example, graphite) of the conductive carbon layer 33 described above as a target. be able to.
  • the adhesion between the interface between the conductive carbon layer 33 and the metal substrate 31 directly adhered thereto and the vicinity thereof is maintained for a long period of time due to intermolecular force and the entry of a few carbon atoms.
  • the metal base 31 is formed before the conductive carbon layer 33 is formed.
  • a step of forming the intermediate layer 32 on at least one surface of the substrate is performed.
  • the same method as described later for the formation of the conductive carbon layer 33 is employed. However, it is necessary to change the target to the constituent material of the intermediate layer 32.
  • the negative bias voltage it is preferable to change the negative bias voltage from a low value to a high value when the intermediate layer 32 is formed.
  • a low bias voltage if it exceeds 0 V is selected so as not to deteriorate the roughness of the interface with the metal substrate 31.
  • the film formation is started at 0V to 50V.
  • the bias voltage is shifted to a high value (usually 50 to 500 V, preferably 100 to 250 V) to grow the columnar crystal thickly.
  • the optimum columnar crystal structure can be controlled through preliminary experiments and the like.
  • film formation may be started at a low bias voltage so as not to deteriorate the roughness of the interface with the metal substrate 31, and for example, initially, it may be over 0V to 50V. After that, there is no problem even if there is a region where the value changes from a high value to a low value, for example, 120V ⁇ 90V ⁇ 200V. This is because when the bias voltage is a low value, the column diameter of the columnar crystal is small, when the bias voltage is high, the column diameter is large, and after that, the column diameter at a high value can be maintained even if it is changed to a low value or the like. Because.
  • the film formation is started at a low bias voltage so as not to deteriorate the roughness of the interface with the metal substrate 31, and then the bias voltage is shifted to a high value. Regardless of the change in voltage thereafter, the columnar crystal can be grown thick.
  • the conductive carbon layer 33 is formed along the thick columnar crystal of the intermediate layer 32.
  • the intermediate layer 32 has a columnar crystal structure and the protruding particles 33a are present on the outermost surface by a simple method of changing the set value of the apparatus. it can.
  • the intermediate layer 32 is formed on the metal base 31 for the first time, in order to thicken the column from the beginning, energy applied to the surface of the metal base 31 is increased, which may cause poor adhesion.
  • the columnar crystal on the metal base 31 side is preferably thinner than the conductive carbon layer 33 side. Therefore, at the initial stage of forming the intermediate layer 32, it is preferable to start the film formation with a low bias voltage so as not to deteriorate the roughness of the interface with the metal substrate 31.
  • the columnar crystals of the intermediate layer 32 can be thickened to the interface with the conductive carbon layer 33, and gaps and defects in the conductive carbon layer 33 formed thereon can be reduced.
  • a sputtering method is preferable as a method for changing the negative bias voltage from a low value to a high value.
  • the conductive carbon layer 33 is also preferably formed by a sputtering method.
  • the intermediate layer 32 formed before that is preferably formed by a similar dry process, particularly by a sputtering method. In this case, since the intermediate layer 32 can be formed by the same method and the same apparatus as the conductive carbon layer 33, the manufacturing process cost can be reduced.
  • the step of forming the intermediate layer 32 it is desirable that a film is formed on the surface of the metal base 31 by sputtering after the surface of the metal base 31 is subjected to pretreatment such as polishing.
  • pretreatment such as polishing.
  • the pretreatment in addition to the polishing treatment, a treatment that is generally performed can be widely adopted. For example, electrolytic polishing, lapping treatment, microshot treatment, etc. can be applied.
  • the intermediate layer 32 and the conductive carbon layer 33 are sequentially formed on the surface of the constituent material of the metal base 31 subjected to the above treatment.
  • the chromium intermediate layer 32 is formed on both surfaces of the metal base 31 (for example, aluminum or an alloy thereof) by the above-described bias change using the constituent material of the intermediate layer 32 (for example, chromium) as a target.
  • Laminate the layer 33 containing conductive carbon is laminated on the surface of the intermediate layer 32 on the surface of the intermediate layer 32 using the constituent material (for example, graphite) of the conductive carbon layer 33 as a target in order.
  • the intermediate layer 32 and the conductive carbon layer 33 can be formed sequentially.
  • the adhesion between the directly attached conductive carbon layer 33, intermediate layer 32, and metal base 31 and its vicinity is maintained for a long period of time due to intermolecular forces and the ingress of slight carbon atoms.
  • a physical vapor deposition (PVD) method such as a sputtering method or an ion plating method, or a filtered cathodic vacuum arc (FCVA) is used.
  • PVD physical vapor deposition
  • FCVA filtered cathodic vacuum arc
  • ion beam deposition methods examples include a magnetron sputtering method, an unbalanced magnetron sputtering (UBMS) method, a dual magnetron sputtering method, and an ECR sputtering method.
  • UBMS unbalanced magnetron sputtering
  • ECR sputtering method examples of the ion plating method include an arc ion plating method.
  • sputtering method and an ion plating method it is preferable to use sputtering method and an ion plating method, and it is especially preferable to use sputtering method.
  • a carbon layer having a low hydrogen content can be formed.
  • the ratio of bonds between carbon atoms (sp 2 hybrid carbon) can be increased, and excellent conductivity is achieved.
  • the film can be formed at a relatively low temperature, and there is an advantage that damage to the metal substrate 31 can be minimized.
  • the intermediate layer 32 having the columnar crystal structure can be obtained by controlling the bias voltage or the like.
  • the intermediate layer 32 and the conductive carbon layer 33 are formed by the sputtering method, it is preferable to apply a negative bias voltage to the metal substrate 31 during the sputtering.
  • the intermediate carbon layer 32 having the columnar crystal structure and the conductive carbon layer 33 in which graphite clusters are densely assembled are formed by the ion irradiation effect.
  • Such an intermediate layer 32 can enhance the anticorrosive effect of the metal substrate 31 and can be applied as the metal substrate 31 even in the case of a metal that is easily corroded such as aluminum.
  • the conductive carbon layer 33 exhibits excellent conductivity, the metal separator 5 having a low contact resistance with other members (for example, the MEA 9) is provided.
  • the absolute value of the negative bias voltage to be applied is not particularly limited, and a voltage capable of forming the conductive carbon layer 33 is employed.
  • the magnitude of the applied voltage is preferably 50 to 500V, more preferably 100 to 300V.
  • a method of changing the negative bias voltage during film formation from a low value to a high value is suitable. Specifically, as in the examples described later, in the initial stage of film formation of the intermediate layer 32, film formation is started with a low bias voltage (above 0 V to 50 V), and then the bias voltage is increased to a high value (usually 50 to 500 V). (Preferably, the columnar crystal structure is grown thickly by shifting to 100 to 250 V).
  • film formation may be started with a low bias voltage, and thereafter, there is a region where the value changes from a high value to a low value, such as 120V ⁇ 90V ⁇ 200V. There is no problem even if it exists.
  • the conductive carbon layer 33 is formed by the UBMS method, it is preferable to form the intermediate layer 32 in advance by the same apparatus and manufacturing method, and form the conductive carbon layer 33 thereon. Thereby, the intermediate
  • the intermediate layer 32 may be formed by another method or apparatus, and the conductive carbon layer 33 may be formed by a different apparatus or manufacturing method. Even in this case, the intermediate layer 32 and the conductive carbon layer 33 having excellent adhesion to the metal substrate 31 are formed.
  • the conductive carbon layer 33 is formed on the metal base material 31 by another method or apparatus, the conductivity excellent in adhesion to the metal base material 31 even when the intermediate layer 32 is not present.
  • the carbon layer 33 is formed.
  • the intermediate layer 32 and the conductive carbon layer 33 are formed on one surface of the metal substrate 31.
  • the intermediate layer 32 and the conductive carbon layer 33 are formed on the other surface of the metal substrate 31 by the same method. Just do it.
  • a conductive member in which the intermediate layer 32 and the conductive carbon layer 33 are formed at the same time on both surfaces of the metal base 31 is manufactured.
  • a commercially available film forming apparatus double-sided simultaneous sputtering film forming apparatus
  • the intermediate layer 32 and the conductive carbon layer 33 are formed on one surface of the metal substrate 31, and then the intermediate layer 32 and the conductive carbon layer 33 are formed on the other surface of the metal substrate 31.
  • the conductive carbon layer 33 may be formed sequentially. Alternatively, first, the intermediate layer 32 is formed on one surface of the metal base 31 and then the intermediate layer 32 is formed on the other surface in an apparatus using chromium as a target. Thereafter, the target is switched to carbon, and the conductive carbon layer 33 is formed on the intermediate layer 32 formed on one surface, and then the conductive carbon layer 33 is formed on the other surface.
  • the same technique as that for forming the film on one surface is employed.
  • FIG. 19 is a schematic plan view of a manufacturing apparatus for depositing at least one of the intermediate layer 32 and the conductive carbon layer 33 using a sputtering method.
  • a sputtering apparatus an apparatus applicable to the unbalanced magnetron sputtering method used in the examples is shown.
  • FIG. 20 is a schematic plan view of a manufacturing apparatus for forming at least one of the intermediate layer 32 and the conductive carbon layer 33 using the arc ion plating method.
  • FIG. 19 and FIG. 20 show an example in which an existing disk-shaped wafer is set in place of the flat metal separator 5 before the uneven pressing.
  • one or more metal separators 5 are arranged on the rotating tables 301 and 401. And in order to form into a film on the front and back of each metal separator 5, each metal separator 5 itself rotates in the direction orthogonal to the rotating shaft of a table. In the arrow directions of the tables 301 and 401 and the metal separator 5, the rotation axes are orthogonal to each other.
  • the vacuum chambers 303 and 403 are maintained at a level of 10 ⁇ 1 to 10 ⁇ 2 Torr, and an inert gas (N 2 , Ar, etc.) can be introduced from the air supply ports 305 and 405 as necessary.
  • an inert gas N 2 , Ar, etc.
  • unnecessary gas is appropriately exhausted from the exhaust ports 307 and 407.
  • Temperature control equipment is connected to the vacuum chambers 303 and 403 and the tables 301 and 401 themselves holding the metal separators 5 so that the temperature can be adjusted.
  • the oxide film present on the surface of the metal separator 5 is removed from the surface of each metal separator 5 with Ar ion bombardment. Since the oxide film is formed with a thickness of several angstroms, the removal time may be several seconds to several minutes.
  • Cr is disposed as the intermediate layer 32 before the conductive carbon layer 33 is formed. For this reason, Cr targets 309 and 409 are disposed in the chambers 301 and 401, respectively. After the formation of the intermediate layer 32 of Cr, the conductive carbon layer 33 is formed using the carbon targets 311 and 411 disposed in the same chambers 301 and 401 continuously.
  • the intermediate layer 32 may be formed without changing the bias voltage or the like at a predetermined value, or may be formed twice or more times. May be. At this time, the film may be formed while continuously changing the bias voltage.
  • the metal separator 5 can be continuously formed by changing the bias voltage, temperature, degree of vacuum, etc. (see Example I-8).
  • the formation of the conductive carbon layer 33 may be performed without changing the bias voltage or the like at a predetermined value, or may be performed twice or more.
  • the conductive carbon layer 33 is preferably sputtered using a solid (such as carbon graphite) as a target because the conductivity tends to decrease due to the presence of hydrogen in the carbon molecules forming the layer.
  • the carbon target 411 can be used as the target as in FIG. .
  • the carbon target 411 By disposing another vapor deposition source 413 for arc discharge, it is possible to form a film in the same chamber 401 without reducing the degree of vacuum.
  • the voltage, current, vacuum degree, temperature, and bias of the arc power source 415 are obtained. It may be performed without changing the voltage or the like, or may be changed as appropriate.
  • the conductive carbon layer 33 is formed by, for example, using the apparatus shown in FIG. 19 or FIG. 20, after the deposition of the intermediate layer 32, after changing the target, and at least one of bias voltage, temperature, vacuum degree, and supply gas amount. It is desirable to change the above and form the same batch. This is excellent in that the conductive carbon layer 33 can be continuously formed after the intermediate layer 32 is formed, and can be formed on the same film formation process, so that the cost is low.
  • the intermediate layer 32 and the conductive carbon layer 33 are formed by sputtering using the apparatus shown in FIG. 19 (Examples I-1 to 5 and 8 to 9), or the apparatus shown in FIG. It is desirable to use the AIP method (see Example I-6) or the ECR sputtering method (see Example I-7). This is because, by using a sputtering or AIP method, a conductive path from one surface of the conductive carbon layer 33 to the other surface is secured, so that excellent electrical conductivity is sufficiently secured and corrosion resistance is further improved. A further improved conductive member can be provided. Further, by using sputtering or the AIP method, it is possible to form an intermediate layer that suppresses an increase in contact resistance while sufficiently ensuring excellent conductivity.
  • a solid source eg, graphite carbon
  • a gas source it is difficult to produce a high quality gas type currently used. This is because hydrogen enters the intermediate layer 32 and the conductive carbon layer 33 and the conductivity decreases. Note that the size and number of the targets 309, 311, 409, 411, and 413 can be adjusted as appropriate depending on the size and the processing amount of the metal separator 5.
  • the intermediate layer 32 and the conductive carbon layer 33 of the present embodiment can be applied anywhere as long as they are not only the metal separator 5 but also the surface of a component that requires conductivity and corrosion resistance.
  • current collecting plates 30 and 40 (see FIG. 14) disposed at both ends of the stack 20 in which a plurality of cells are stacked, terminal connection portions (see output terminals 37 and 47 in FIG. 14) for monitoring voltage, etc. Can be mentioned.
  • the conductive member of this embodiment is used for various purposes.
  • a typical example is the metal separator 5 of the cell unit 1 shown in FIG.
  • the use of the conductive member of the present embodiment is not limited to this.
  • various fuel cell separators such as phosphoric acid fuel cell (PAFC), molten carbonate fuel cell (MCFC), solid electrolyte fuel cell (SOFC) or alkaline fuel cell (AFC) Can also be used.
  • PAFC phosphoric acid fuel cell
  • MCFC molten carbonate fuel cell
  • SOFC solid electrolyte fuel cell
  • AFC alkaline fuel cell
  • it is used in various applications that require both conductivity and corrosion resistance. Examples of applications in which the conductive member of the present embodiment is used include other fuel cell components (current collector plate, bus bar, gas diffusion base, MEA), contacts of electronic components, and the like.
  • the conductive member of the present embodiment can be used in a wet environment and an energized environment. When used in such an environment, the effect of the present invention of achieving both conductivity and corrosion resistance is remarkably exhibited.
  • the “humid environment” refers to an environment where the relative humidity of the atmosphere in contact with the conductive member is 30 RH or higher. The relative humidity is preferably 30% RH or more, more preferably 60% RH or more, and particularly preferably 100% RH or more.
  • the “energization environment” in which the conductive member of the present embodiment is used refers to an environment in which current flows through the conductive member at a current density of 0.001 A / cm 2 or more. The current density is preferably 0.01 A / cm 2 or more.
  • FIGS. 1 to 4, 13, 14 and the like components of the PEFC using the metal separator 5 formed of the conductive member of the present embodiment will be described with reference to FIGS. 1 to 4, 13, 14 and the like.
  • the present embodiment is characterized by the conductive member constituting the separator. Therefore, the specific form such as the shape of the metal separator 5 in the cell unit 1 and the specific form of members other than the metal separator 5 constituting the fuel cell are appropriately modified with reference to conventionally known knowledge.
  • Is given. 13 is a schematic cross-sectional view for explaining an example of a fuel cell stack configuration in which a plurality of cell unit configurations of the fuel cell of FIG. 1 are stacked
  • FIG. 14 is a perspective view of the fuel cell stack configuration of FIG. It is.
  • the electrolyte membrane 2 is composed of a solid polymer electrolyte membrane 2 as shown in FIGS.
  • the solid polymer electrolyte membrane 2 has a function of selectively transmitting protons generated in the anode catalyst layer 3a during PEFC operation to the cathode catalyst layer 3b along the film thickness direction.
  • the solid polymer electrolyte membrane 2 also has a function as a partition wall for preventing the fuel gas 5ag supplied to the anode side and the oxidant gas 5bg supplied to the cathode side from being mixed.
  • the solid polymer electrolyte membrane 2 is roughly classified into a fluorine-based polymer electrolyte membrane and a hydrocarbon-based polymer electrolyte membrane depending on the type of ion exchange resin that is a constituent material.
  • ion exchange resins constituting the fluorine-based polymer electrolyte membrane include Nafion (registered trademark, manufactured by DuPont), Aciplex (registered trademark, manufactured by Asahi Kasei Co., Ltd.), Flemion (registered trademark, manufactured by Asahi Glass Co., Ltd.), and the like.
  • Perfluorocarbon sulfonic acid polymer perfluorocarbon phosphonic acid polymer, trifluorostyrene sulfonic acid polymer, ethylene tetrafluoroethylene-g-styrene sulfonic acid polymer, ethylene-tetrafluoroethylene copolymer, polyvinylidene fluoride- Examples include perfluorocarbon sulfonic acid polymers. From the viewpoint of improving power generation performance such as heat resistance and chemical stability, these fluorine-based polymer electrolyte membranes are preferably used, and particularly preferably fluorine-based polymer electrolytes composed of perfluorocarbon sulfonic acid polymers. A membrane is used.
  • hydrocarbon electrolytes include sulfonated polyethersulfone (S-PES), sulfonated polyaryletherketone, alkylsulfonated polybenzimidazole, alkylphosphonated polybenzimidazole, sulfonated polystyrene, and sulfonated poly Examples include ether ether ketone (S-PEEK) and sulfonated polyphenylene (S-PPP).
  • S-PES sulfonated polyethersulfone
  • S-PEEK ether ketone
  • S-PPP sulfonated polyphenylene
  • the thickness of the electrolyte membrane 2 may be appropriately determined in consideration of the characteristics of the obtained fuel cell, and is not particularly limited.
  • the thickness of the electrolyte layer is usually about 5 ⁇ m to 300 ⁇ m. When the thickness of the electrolyte layer is within such a range, the balance of strength during film formation, durability during use, and output characteristics during use is appropriately controlled.
  • the catalyst layers 3 (the anode catalyst layer 3a and the cathode catalyst layer 3b) shown in FIGS. 1 and 13 are layers in which the cell reaction actually proceeds. Specifically, the oxidation reaction of hydrogen proceeds in the anode catalyst layer 3a, and the reduction reaction of oxygen proceeds in the cathode catalyst layer 3b.
  • the catalyst layer 3 contains a catalyst component, a conductive catalyst carrier that supports the catalyst component, and an electrolyte.
  • a composite in which a catalyst component is supported on a catalyst carrier is also referred to as an “electrode catalyst”.
  • the catalyst component used in the anode catalyst layer 3a is not particularly limited as long as it has a catalytic action in the oxidation reaction of hydrogen, and a known catalyst can be used.
  • the catalyst component used for the cathode catalyst layer 3b is not particularly limited as long as it has a catalytic action for the oxygen reduction reaction, and a known catalyst can be used. Specifically, it is selected from metals such as platinum, ruthenium, iridium, rhodium, palladium, osmium, tungsten, lead, iron, chromium, cobalt, nickel, manganese, vanadium, molybdenum, gallium, aluminum, and alloys thereof. .
  • those containing at least platinum are preferably used in order to improve catalytic activity, poisoning resistance to carbon monoxide, heat resistance, and the like.
  • the composition of the alloy depends on the type of metal to be alloyed, the content of platinum is preferably 30 to 90 atomic%, and the content of the metal to be alloyed with platinum is preferably 10 to 70 atomic%.
  • an alloy is a general term for a metal element having one or more metal elements or non-metal elements added and having metallic properties.
  • the eutectic alloy which is a mixture of the component elements to form separate crystals, the component elements are completely melted into a solid solution, the component element is an intermetallic compound or a compound of a metal and a nonmetal.
  • the catalyst component used for the anode catalyst layer 3a and the catalyst component used for the cathode catalyst layer 3b are appropriately selected from the above.
  • descriptions of the catalyst components for the anode catalyst layer and the cathode catalyst layer have the same definition for both. Therefore, they are collectively referred to as “catalyst components”.
  • the catalyst components of the anode catalyst layer 3a and the cathode catalyst layer 3b do not need to be the same, and are appropriately selected so as to exhibit the desired action as described above.
  • the shape and size of the catalyst component are not particularly limited, and the same shape and size as known catalyst components are employed. However, the shape of the catalyst component is preferably granular. At this time, the average particle diameter of the catalyst particles is preferably 1 nm to 30 nm. When the average particle size of the catalyst particles is within such a range, the balance between the catalyst utilization rate related to the effective electrode area where the electrochemical reaction proceeds and the ease of loading is appropriately controlled.
  • the “average particle diameter of the catalyst particles” in the present specification is the crystallite diameter determined from the half-value width of the diffraction peak of the catalyst component in X-ray diffraction or the particle diameter of the catalyst component determined from a transmission electron microscope image. Measured as an average value.
  • the catalyst carrier functions as a carrier for supporting the above-described catalyst component and an electron conduction path involved in the transfer of electrons between the catalyst component and another member.
  • the catalyst carrier may be any catalyst carrier as long as it has a specific surface area for supporting the catalyst component in a desired dispersed state and has sufficient electron conductivity, and the main component is preferably carbon. Specific examples include carbon particles made of carbon black, activated carbon, coke, natural graphite, artificial graphite and the like. “The main component is carbon” means that the main component contains carbon atoms, and is a concept that includes both carbon atoms and substantially carbon atoms. In some cases, elements other than carbon atoms may be included in order to improve the characteristics of the fuel cell. Incidentally, “substantially consisting of carbon atoms” means that contamination of about 2 to 3% by mass or less of impurities is allowed.
  • the BET specific surface area of the catalyst carrier may be a specific surface area sufficient to carry the catalyst component in a highly dispersed state, but is preferably 20 to 1600 m 2 / g, more preferably 80 to 1200 m 2 / g. When the specific surface area of the catalyst support is within this range, the balance between the dispersibility of the catalyst component on the catalyst support and the effective utilization rate of the catalyst component is appropriately controlled.
  • the size of the catalyst carrier is not particularly limited, but from the viewpoint of easy loading, catalyst utilization, and catalyst layer thickness control within an appropriate range, the average particle size is about 5 to 200 nm, preferably 10 to 10 nm. About 100 nm is preferable.
  • the amount of the catalyst component supported is preferably 10 to 80% by mass, more preferably 30 to 70% by mass, based on the total amount of the electrode catalyst.
  • the supported amount of the catalyst component is within such a range, the balance between the degree of dispersion of the catalyst component on the catalyst carrier and the catalyst performance is appropriately controlled.
  • the amount of the catalyst component supported on the electrode catalyst is measured by inductively coupled plasma emission spectroscopy (ICP).
  • the catalyst layer 3 contains an ion conductive polymer electrolyte in addition to the electrode catalyst.
  • the said polymer electrolyte is not specifically limited, A conventionally well-known knowledge is referred suitably.
  • the ion exchange resin which comprises the electrolyte membrane 2 mentioned above is added to the catalyst layer 3 as a polymer electrolyte.
  • GDL Gas diffusion layer
  • the material constituting the base material of the gas diffusion layer 4 (4a, 4b) is not particularly limited.
  • a sheet-like material having conductivity and porosity such as a carbon woven fabric, a paper-like paper body, a felt, and a non-woven fabric can be used.
  • the thickness of the base material of the gas diffusion layer 4 may be appropriately determined in consideration of the characteristics of the obtained gas diffusion layer 4, but may be about 30 ⁇ m to 500 ⁇ m. If the thickness of the base material of the gas diffusion layer 4 is a value within such a range, the balance between the mechanical strength and the diffusibility of gas, water, and the like is appropriately controlled.
  • the gas diffusion layer 4 preferably contains a water repellent for the purpose of further improving the water repellency and preventing the flooding phenomenon.
  • the water repellent include fluorine-based polymer materials such as polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), polyhexafluoropropylene, tetrafluoroethylene-hexafluoropropylene copolymer (FEP), polypropylene, Examples include polyethylene.
  • the gas diffusion layer 4 may have a carbon particle layer made of an aggregate of carbon particles containing a water repellent on the catalyst layer side of the base material.
  • carbon particles contained in the carbon particle layer conventionally known materials such as carbon black, graphite, and expanded graphite are appropriately employed.
  • carbon blacks such as oil furnace black, channel black, lamp black, thermal black, and acetylene black are preferably used because of excellent electron conductivity and a large specific surface area.
  • the average particle diameter of the carbon particles is preferably about 10 nm to 100 nm.
  • water repellent used for the carbon particle layer examples include the same water repellents as described above. Of these, fluorine-based polymer materials are preferably used because of their excellent water repellency and corrosion resistance during electrode reaction.
  • the mixing ratio of the carbon particles to the water repellent in the carbon particle layer is about 90:10 to 40:60 (carbon particles: water repellent) in mass ratio in consideration of the balance between water repellency and electron conductivity. Is good.
  • the thickness of the carbon particle layer may be appropriately determined in consideration of the water repellency of the obtained gas diffusion layer, but is preferably 10 to 1000 ⁇ m, more preferably 50 to 500 ⁇ m.
  • a single cell 1 includes a fuel electrode composed of an electrode catalyst layer 3a and a gas diffusion layer 4a, an oxygen electrode composed of an electrode catalyst layer 3b and a gas diffusion layer 4b on both sides of the solid polymer electrolyte membrane 2.
  • the fuel gas 5ag and the oxidant gas 5bg supplied to the MEA 9 are supplied to the anode separator 5a and the cathode separator 5b through the fuel gas flow path 5aa, the oxidant gas flow path 5bb, and the like.
  • a stack of single cells 1 or two or more stacked one by one is further fastened by a pair of end plates, that is, a fuel electrode side end plate 70 and an oxygen electrode side end plate 80 from both sides in the thickness direction (see FIG. 14).
  • This fuel cell is used as a power source.
  • Applications of the power source include, for example, stationary devices, consumer portable devices such as mobile phones, emergency devices, outdoor devices such as leisure and construction power sources, and mobile objects such as automobiles with limited mounting space.
  • the mobile power source is required to have a high output voltage after a relatively long time of operation stop.
  • the thickness and cost can be reduced through components (conductive members) such as the metal separator 5 and the current collector plates 30 and 40, and the output density of the fuel cell can be reduced. Can contribute to improvement. Therefore, the vehicle weight can be reduced and the vehicle cost can be reduced.
  • the vehicle when a fuel cell of the same volume is installed, the vehicle can run for a longer distance, and the acceleration performance can be improved.
  • the conductive members such as the metal separator 5 and the current collector plates 30 and 40 of the fuel cell are excellent in corrosion resistance, and the durability of the fuel cell stack 20 can be improved and the life can be extended.
  • the current collector plates 30 and 40, insulating plates 50 and 60, and end plates 70 and 80 are disposed on both sides of the stack 20.
  • the current collecting plates 30 and 40 are made of a gas impermeable conductive member such as dense carbon, copper plate, or aluminum plate. Further, output terminals 37 and 47 for outputting electromotive force generated in the stack 20 are provided.
  • the insulating plates 50 and 60 are formed from an insulating member such as rubber or resin.
  • the conductive member of this embodiment is employed. be able to. Copper plates and aluminum plates are thinner and lighter than stainless steel, but have poor corrosion resistance.
  • the intermediate layer and the conductive carbon layer it is possible to reduce the electrical resistance on the outermost surface of the conductive carbon layer while preventing the corrosion of the aluminum plate due to the ingress of droplets in the intermediate layer. As a result, the chemical stability can be maintained even if the metal current collector plates 30 and 40 are exposed to an acidic atmosphere while maintaining the conductivity. That is, as shown in FIG. 13, current collector plates 30 and 40 that can suppress ion elution due to defects such as pinholes without increasing the contact resistance with metal separator 5 can be provided.
  • the end plates 70 and 80 are formed of a material having rigidity, for example, a metal material such as steel.
  • the end plates 70, 80 have a fuel gas inlet 71, a fuel gas outlet 72, an oxidant gas inlet 74, an oxidant gas outlet 75, a cooling water inlet 77 and a cooling water outlet 78.
  • the fuel gas inlet 71, the fuel gas outlet 72, the oxidant gas inlet 74, the oxidant gas outlet 75, the cooling water inlet 77 and the cooling water outlet 78 are the fuel gas 5ag, the oxidant gas 5bg and the cooling water.
  • it communicates with the fuel gas channel 5aa, the oxidant gas channel 5bb and the cooling water channel 8.
  • through holes through which the tie rods 90 are inserted are arranged at the four corners of the stack 20, the current collecting plates 30, 40, the insulating plates 50, 60, and the end plates 70, 80.
  • the tie rod 90 is screwed with a nut (not shown) to a male screw formed at an end thereof, and fastens the fuel cell stack 20 with end plates 70 and 80.
  • the load for forming the stack 20 acts in the stacking direction of the fuel cell single cells 1 to hold the single cells 1 in a pressed state.
  • the tie rod 90 is formed of a material having rigidity, for example, a metal material such as steel. Further, the tie rod 90 has an insulated surface in order to prevent an electrical short circuit between the fuel cell single cells 201.
  • the number of tie rods 90 installed is not limited to four (four corners). Further, the fastening mechanism of the tie rod 90 is not limited to screwing, and other means can be applied.
  • the gasket is a seal member disposed so as to surround the outer periphery of the separator 5 located on the surface of the MEA 9.
  • the gasket may be fixed to the outer surface of the electrolyte membrane 2 of the MEA 9 via an adhesive layer (not shown).
  • the gasket has a function of ensuring a sealing property between the separator 5 and the MEA 9.
  • the adhesive layer used as necessary preferably corresponds to the shape of the gasket and is arranged in a frame shape on the entire peripheral edge of the electrolyte membrane in consideration of securing adhesiveness.
  • the manifold (fuel gas inlet 71, fuel gas outlet 72, oxidant gas inlet 74, oxidant gas outlet 75, cooling water inlet 77, and cooling It is desirable to form the intermediate layer 32 on the inner wall of the through hole of the water discharge port 78). That is, the inner wall of the through hole of the manifold does not require conductivity, and therefore it is desirable to form an intermediate layer (Cr layer) without providing a conductive carbon layer. Thereby, corrosion of the through hole of the manifold can be effectively prevented.
  • the configuration of the present embodiment can be adopted for the components (conductive members) of the fuel cell that require conductivity and corrosion resistance.
  • the said electrically-conductive member and by extension, a fuel cell stack can be reduced in thickness and weight, and an output density can be improved.
  • the manufacturing method of the fuel cell of the present embodiment is not particularly limited, and conventionally known knowledge can be appropriately referred to in the field of the fuel cell.
  • the type of fuel gas used when operating the fuel cell is not limited to hydrogen.
  • hydrogen in addition to hydrogen, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 3-butanol, dimethyl ether, diethyl ether, ethylene glycol, diethylene glycol and the like are used.
  • hydrogen and methanol are preferably used in that high output is possible.
  • the metal separator 5 is shape
  • the concave and convex shapes constituting the gas flow paths 5aa and 5bb and the refrigerant flow path 8 are formed in advance by cutting a flat metal plate, and the conductive carbon layer 33 is formed on the surface by the above-described method.
  • the metal separator 5 may be formed by forming the intermediate layer 32.
  • FIG. 10 is a conceptual diagram of a vehicle equipped with the fuel cell stack.
  • the fuel cell stack 200 in order to mount the fuel cell stack 200 on a vehicle such as the fuel cell vehicle 210, for example, the fuel cell stack 200 may be mounted under the seat at the center of the vehicle body of the fuel cell vehicle 210. If it is mounted under the seat, the interior space and the trunk room can be widened.
  • the place where the fuel cell stack 200 is mounted is not limited to the position under the seat, but may be a lower part of the rear trunk room or an engine room in front of the vehicle 210.
  • the vehicle 210 carrying the cell unit 1 and the fuel cell stack 200 is also included in the technical scope of the present invention.
  • the cell unit 1 and the fuel cell stack 200 are excellent in output characteristics and durability. Therefore, a highly reliable fuel cell vehicle 210 is provided over a long period of time.
  • Example I-1 A stainless steel plate (SUS316L) was prepared as a constituent material of the metal base 31 constituting the conductive member.
  • the thickness of the stainless steel plate is 100 ⁇ m.
  • This stainless steel plate was ultrasonically cleaned in an aqueous ethanol solution for 3 minutes as a pretreatment. Next, the cleaned stainless steel plate was placed in a vacuum chamber, and ion bombardment with Ar gas was performed to remove the oxide film on the surface. The pretreatment and ion bombardment described above were both performed on both surfaces of the stainless steel plate.
  • each of both surfaces of the stainless steel plate is made of 0.2 ⁇ m thick Cr.
  • An intermediate layer 32 was formed.
  • Example I-1 a conductive member of Example I-1 was produced.
  • Example I-2 Except that the magnitude (absolute value) of the negative bias voltage applied when forming the conductive carbon layer 33 was 140 V, the same method as in Example I-1 was used. A conductive member was produced.
  • Example I-3 Except that the magnitude (absolute value) of the negative bias voltage applied when forming the conductive carbon layer 33 was set to 300 V, the method of Example I-3 was performed in the same manner as Example I-1 described above. A conductive member was produced.
  • Example I-4 Except that the magnitude (absolute value) of the negative bias voltage applied when forming the conductive carbon layer 33 was set to 450 V, the method of Example I-4 was performed in the same manner as Example I-1 described above. A conductive member was produced.
  • Example I-5 A conductive member of Example I-5 was produced by the same method as Example I-2 described above except that the material constituting the metal base 31 was aluminum (aluminum A1050).
  • Example I-6 A conductive member of Example I-6 was produced by the same method as Example I-2 described above except that the method of forming the intermediate layer 32 and the conductive carbon layer 33 was the arc ion plating method.
  • Example I-7 The conductive member of Example I-7 was formed in the same manner as in Example I-1 described above except that the conductive carbon layer 33 was formed directly on the stainless steel plate by ECR sputtering without forming the intermediate layer 32. Was made.
  • Comparative Example I-1 The same as Example I-1 described above, except that the intermediate carbon layer 32 was not formed, the conductive carbon layer 33 was formed directly on the stainless steel plate, and no negative bias voltage was applied during the formation. A conductive member of Comparative Example I-1 was produced by the method.
  • Comparative Example I-2 A conductive member of Comparative Example I-2 was produced by the same method as Example I-1 described above, except that a negative bias voltage was not applied when the conductive carbon layer 33 was formed.
  • Comparative Example I-3 The conductive member of Comparative Example I-3 was prepared in the same manner as in Example I-1 described above except that the method of forming the intermediate layer 32 and the conductive carbon layer 33 was a plasma chemical vapor deposition (CVD) method. Was made.
  • CVD plasma chemical vapor deposition
  • Comparative Example I-4 A conductive member of Comparative Example I-4 was produced by the same method as Example I-1 described above, except that the method of forming the intermediate layer 32 and the conductive carbon layer 33 was an ionized vapor deposition method.
  • Comparative Example I-5 The above-described implementation is performed except that the method of forming the conductive carbon layer 33 without forming the intermediate layer 32 is a thermal chemical vapor deposition (CVD) method, and the thickness of the conductive carbon layer 33 is 0.08 ⁇ m.
  • a conductive member of Comparative Example I-5 was produced in the same manner as in Example I-1.
  • the film-forming temperature at the time of implementing thermal CVD was set to 850 degreeC.
  • Example I-8 An aluminum plate (aluminum A1050) was prepared as a constituent material of the metal base 31 constituting the conductive member. The thickness of the aluminum plate is 200 ⁇ m. Using this aluminum plate, ultrasonic cleaning was performed in ethanol solution for 3 minutes as a pretreatment, and then the metal substrate 31 was placed in a vacuum chamber, and ion bombardment with Ar gas was performed to remove the oxide film on the surface. . Both the pretreatment and the ion bombardment treatment were performed on both surfaces of the metal substrate 31.
  • a Cr film (intermediate layer A) having a film thickness of 0.1 ⁇ m is formed on both surfaces of the metal base 31 using Cr as a target and applying a negative bias voltage of 50 V by an unbalanced magnetron sputtering method. I let you.
  • a Cr layer having a thickness of 1 ⁇ m was formed on both surfaces of the metal base 31 while applying a negative bias voltage of 200 V to the metal base 31 on the intermediate layer A.
  • the intermediate layer 32 including the intermediate layer A is included in the Cr layer.
  • this intermediate layer 32 a solid graphite is used as a target by the UBMS method, and a negative bias voltage having a magnitude of 140 V is applied to the aluminum plate, while Cr layers (intermediate layer) on both sides of the aluminum plate are applied.
  • Example I-9 An aluminum plate (aluminum A1050) was prepared as a constituent material of the metal base 31 constituting the conductive member.
  • the thickness of the aluminum plate is 200 ⁇ m.
  • ultrasonic cleaning was performed in ethanol solution for 3 minutes as a pretreatment, and then the metal substrate 31 was placed in a vacuum chamber, and ion bombardment with Ar gas was performed to remove the oxide film on the surface. .
  • Both the pretreatment and the ion bombardment treatment were performed on both surfaces of the metal substrate 31.
  • a Cr layer having a thickness of 1 ⁇ m was formed on both surfaces of the metal substrate 31 by using unbalanced magnetron sputtering method while using Cr as a target and applying a negative bias voltage of 50V. Note that only the Cr layer becomes the intermediate layer 32.
  • this intermediate layer 32 a solid graphite is used as a target by the UBMS method, and a negative bias voltage having a magnitude of 140 V is applied to the aluminum plate, while Cr layers (intermediate layer) on both sides of the aluminum plate are applied.
  • the conductive member produced in each of the above Examples I-1 to 9 and Comparative Examples I-1 to I-5 was measured for the R value of the conductive carbon layer 33. Specifically, first, the Raman spectrum of the conductive carbon layer 33 was measured using a microscopic Raman spectrometer. Then, 1300 ⁇ 1400 cm peak intensity of D-band located -1 (I D), 1500 ⁇ 1600cm peak intensity of G-band located -1 (I G) and the peak area ratio of the (I D / I G) was calculated as an R value. The obtained results are shown in Table 1 below.
  • the intensity ratio R (I D / I G ) is expressed as “D / G”.
  • the intensity ratio R (I D / I G ) is also simply abbreviated as “R value”.
  • the Vickers hardness (Hv) of the conductive carbon layer 33 in the conductive members produced in Examples I-1 to I-9 were all 1500 Hv or less.
  • each conductive member (metal separator 5) formed in each of Examples I-1 to I-9 and Comparative Examples I-1 to I-5 was cut into a size of 30 mm ⁇ 30 mm, and 80 The sample was immersed in acidic water at a temperature of 100 ° C. for 100 hours, and the contact resistance values before and after the immersion test were measured.
  • each of Examples I-1 to I-7 and Comparative Examples I-1 to I-5 had a pH of 4 or less
  • Examples I-8 to I-9 had a pH of 6 or less.
  • Table 1 The results obtained are shown in Table 1 below. Moreover, the graph corresponding to the result regarding the contact resistance shown in Table 1 is shown to FIG. 12A and 12B. In the graph shown in FIG. 12A, the vertical axis is a logarithmic scale, and the value of the contact resistance on the vertical axis is shown as a relative value.
  • the conductive members produced in Examples I-1 to I-9 differ from those in Comparative Examples I-1 to I-5 after the immersion test. Even so, the contact resistance can be suppressed to an extremely small value.
  • Example I-8 despite the fact that corroded aluminum is used for the metal substrate 31, it is compared with the cases of other Examples I-5 and I-9. Even so, the contact resistance can be suppressed to a very small value. In addition, the conductive member of Example I-8 has a very low contact resistance even after the immersion test. It was also confirmed that the corrosion resistance comparable to the other Examples I-1 to I-4 and I-6 to I-7 using stainless steel for the metal substrate 31 can be maintained.
  • the conductive member of Example I-8 uses aluminum that is easily corroded for the metal base material 31, it is compared with the conductive member of Example I-9 that uses the same aluminum. The effect can be enhanced. Specifically, the conductive member of Example I-8 has an Al elution amount of 500 ppb even after the above immersion test, compared with the Al elution amount of 1500 ppb of the conductive member of Example I-9. It can be suppressed to an extremely small value. From this, when the intermediate layer 32 is provided between the conductive carbon layer 33 and the metal substrate 31 as in Example I-8 and the protruding particles 33a are present on the outermost surface, it is excellent. It has been confirmed that the increase in contact resistance can be suppressed while sufficiently ensuring the electrical conductivity, and the anticorrosion effect of the metal substrate 31 can be further enhanced.
  • FIGS. 15a and 15b are SEM photographs observing the surfaces of Example I-9 and Example I-8.
  • the protruding particles 33a are present on the outermost surface of the conductive member, and at least 30 protruding particles 33a per 100 ⁇ m 2. Whether or not it exists can be easily confirmed.
  • FIGS. 16a and 16b are enlarged views of the SEM photographs of FIGS. 15a and 15b.
  • the presence or absence of the protruding particles 33a can be easily confirmed on the outermost surface of the conductive member, and the protrusion having a diameter of 200 to 500 nm on the outermost surface can be confirmed. It is also possible to confirm the appearance of the mixed particles 33a and the fine particles 33b having a diameter of 50 to 100 nm and the size of each particle.
  • FIGS. 17a and 17b are TEM photographs of the cross sections of Example I-9 and Example I-8.
  • FIGS. 18a and 18b are SEM photographs of the cross sections of Example I-9 and Example I-8.
  • the thickness of the columnar crystal in the cross section of the intermediate layer 32 can be measured, and the average value of the thickness of the columnar crystal in the cross section of the intermediate layer 32 is 200 nm. It can also be confirmed whether it is in the range of ⁇ 500 nm.
  • the height of the protruding particles 33a with respect to the peripheral portion can be measured, and it can be confirmed that the height protrudes in the range of 100 nm to 500 nm with respect to the peripheral portion.
  • the film thickness of the Cr intermediate layer 32 can be measured, and it can be easily confirmed that the film thickness is in the range of 0.02 ⁇ m to 5 ⁇ m. Further, a columnar crystal having a thickness of 200 nm to 500 nm in the outermost layer can be easily observed, and the crystal having the thickness is what percentage of the entire thickness of the intermediate layer 32 with respect to the direction of the metal substrate 31 from the outermost layer. It can also be measured.
  • UBM 1 is an abbreviation for “UBM sputtering”
  • ECR 3 is an abbreviation for “ECR sputtering”
  • ion 2 is an abbreviation for “ion plating”.
  • Plasma 4 is an abbreviation for “plasma CVD”.
  • “Columnar thickness” in the table refers to the average value of the columnar crystal column thicknesses in the cross section of the intermediate layer 32.
  • “Protruded particle diameter” refers to a particle having a diameter of 200 to 500 nm on the outermost surface (an average value within a range of 200 to 500 nm in diameter).
  • the “number of protruding particles 33a” is the number of particles having a diameter of 200 to 500 nm on the outermost surface.
  • “-” in the “protruding particle diameter” means that there is no particle having a diameter of 200 to 500 nm on the outermost surface as the measurement object.
  • the “projection height” of “ ⁇ ” means the height (average value) of the projection-like particles 33a that are the measurement object, and here, the number of the projection-like particles 33a that are the measurement object is zero. This means that its height cannot be measured.
  • the conductive member (conductive structure) of the present embodiment includes a metal base, a dense barrier layer formed on the metal base, an intermediate layer formed on the dense barrier layer, and the intermediate layer. And a conductive thin film layer to be formed. Furthermore, the dense barrier layer has a lower crystal orientation than the intermediate layer.
  • This embodiment is characterized in that a dense barrier layer with low crystal orientation is disposed between the metal substrate and the intermediate layer.
  • a dense barrier layer with low crystal orientation is disposed between the metal substrate and the intermediate layer.
  • the polymer electrolyte fuel cell (PEFC) according to this embodiment also has the same basic configuration as the PEFC according to the first embodiment. Specifically, as shown in FIG. 1, the PEFC has a solid polymer electrolyte membrane 2 and a pair of catalyst layers (an anode catalyst layer 3a and a cathode catalyst layer 3b) that sandwich the membrane. The laminate of the solid polymer electrolyte membrane 2 and the catalyst layer 3 (3a, 3b) is further sandwiched between a pair of gas diffusion layers 4 (anode gas diffusion layer 4a and cathode gas diffusion layer 4b).
  • the solid polymer electrolyte membrane 2, the pair of catalyst layers 3 (3a, 3b), and the pair of gas diffusion layers 4 (4a, 4b) constitute a membrane electrode assembly 9 in a stacked state.
  • the MEA 9 is further sandwiched between a pair of separators 5 (an anode separator 5a and a cathode separator 5b).
  • FIG. 21 is a cross-sectional view showing a configuration of a separator 5A that is a conductive member of the present embodiment.
  • the separator 5 ⁇ / b> A includes a metal substrate 152, a dense barrier layer 153, an intermediate layer 154, and a conductive thin film layer 155.
  • the separator 5A is arranged so that the conductive thin film layer 155 is located on the MEA 9 side.
  • each component of separator 5A of this embodiment is explained in full detail.
  • the metal base material 152 is a main layer of a conductive member that constitutes the separator 5A, and contributes to ensuring conductivity and mechanical strength. And the metal base material 152 which concerns on this embodiment can use the thing similar to the metal base material 31 of 1st embodiment.
  • the dense barrier layer 153 is disposed on the metal substrate 152. By the presence of this layer, it is possible to suppress or prevent water generated by the electrode from entering the metal substrate 152 side. Therefore, the arrangement of the dense barrier layer 153 ensures that the conductive member constituting the separator 5A has higher corrosion resistance than the case where only the metal substrate 152, the intermediate layer 154, and the conductive thin film layer 155 are provided while ensuring conductivity. Can be improved.
  • the dense barrier layer having a low crystal orientation By disposing the dense barrier layer having a low crystal orientation in this manner between the metal substrate and the intermediate layer, the water generated on the electrode side can easily pass through the conductive thin film layer 155, but the dense barrier layer. The layer hardly passes. For this reason, since water hardly reaches the intermediate layer 154 and the metal base material 152, corrosion of the conductive member can be effectively suppressed.
  • the “dense barrier layer” means a layer that is so dense that water molecules and eluted ions do not pass through. Specifically, the porosity is 10% or less, more preferably 7% or less. It means a certain layer.
  • the lower limit of the porosity of the dense barrier layer is not particularly limited as long as water molecules do not pass therethrough. Specifically, the lower limit of the porosity of the dense barrier layer is about 0.5%, more preferably 0.7%.
  • “porosity” measures the area ratio (%) of the metal, metalloid, metal carbide or metal nitride constituting the dense barrier layer by image analysis of the surface and cross section of the layer with SEM. It is required by doing.
  • the dense barrier layer preferably has a lower crystal orientation than the intermediate layer.
  • the dense barrier layer has a structure in which water molecules generated on the electrode side are difficult to pass through.
  • crystal orientation refers to the degree of orientation of crystal axes in a polycrystalline structure. Therefore, “high crystal orientation” means that each crystal axis exists in the same direction (in parallel) in a polycrystalline structure. On the other hand, “low crystal orientation” means that each crystal axis exists in various directions in a polycrystalline structure.
  • the degree of crystal orientation is determined using JCPDS (ASTM) data, which is considered to be standard data by powder X-ray diffraction, which is generally considered to have substantially no orientation, as an index. can do.
  • JCPDS ASTM
  • “degree of crystal orientation (%)” is obtained from the peak intensity of the Debye intensity distribution on the (121) plane by WAXD measurement.
  • the dense barrier layer can be formed by appropriately selecting the average crystallite size and the forming method of the dense barrier layer so that the crystal orientation is lower than that of the intermediate layer.
  • the dense barrier layer can be formed by making the average crystallite size of the dense barrier layer smaller than the average crystallite size of the intermediate layer.
  • the ratio (D 2 / D 1 ) of the average crystallite diameter [D 2 (nm)] of the dense barrier layer to the average crystallite diameter [D 1 (nm)] of the intermediate layer is 0.1 or more and less than 1. Preferably, it is more preferably 0.1 to 0.5. Within such a range, the crystal orientation of the dense barrier layer can be lowered to the extent that water molecules do not substantially reach the metal substrate.
  • the average crystallite diameter of each layer is not particularly limited as long as the above-described size relationship is satisfied.
  • the average crystallite diameter [D 2 (nm)] of the dense barrier layer is preferably 10 nm or more and less than 30 nm, more preferably 10 nm to 20 nm.
  • the average crystallite diameter [D 1 (nm)] of the intermediate layer is preferably 30 nm to 100 nm, and more preferably 30 nm to 50 nm.
  • the “crystallite diameter” means the crystallite size calculated by the Scherre method in the X-ray diffraction method.
  • the material constituting the dense barrier layer includes Group 4 metals (Ti, Zr, Hf), Group 5 metals (V, Nb, Ta), and Group 6 metals in the periodic table.
  • Metals such as (Cr, Mo, W); metalloids such as Si and B; alloys, carbides and nitrides of the above metals.
  • metals with low ion elution such as chromium (Cr), tungsten (W), titanium (Ti), molybdenum (Mo), niobium (Nb) or hafnium (Hf), or nitrides, carbides or carbonitrides thereof.
  • the product is preferably used.
  • the corrosion resistance of the separator can be significantly improved.
  • the material which comprises the said dense barrier layer may be used independently, or may be used with the form of 2 or more types of mixtures.
  • the material constituting the dense barrier layer is preferably equal to or higher than the thermal expansion coefficient of the material (metal, metal carbide or metal nitride) constituting the intermediate layer described in detail below.
  • the conductive thin film layer is less likely to thermally expand, and the metal substrate is likely to thermally expand.
  • the material constituting the dense barrier layer and the intermediate layer so as to have the above-described thermal expansion coefficient, the metal substrate, the dense barrier layer, the intermediate layer, and the conductive thin film layer are expanded by heat. By suppressing the difference in shrinkage, peeling of each layer can be prevented. In such a case, the adhesion between the intermediate layer and the dense barrier layer can also be improved.
  • the material constituting the dense barrier layer should be metallicly noble to the same extent as the material constituting the intermediate layer described in detail below, or metallic noble compared to the material of the intermediate layer. preferable. Thereby, a potential difference is hardly generated between the dense barrier layer and the intermediate layer, the metal base material is more effectively protected, and the corrosion resistance of the conductive member can be improved.
  • the thickness of the dense barrier layer 153 is not particularly limited. However, from the viewpoint of reducing the size of the fuel cell stack as much as possible by making the separator 5A thinner, the thickness of the dense barrier layer 153 is preferably 0.01 ⁇ m to 10 ⁇ m, and more preferably 0. The thickness is from 05 ⁇ m to 5 ⁇ m, more preferably from 0.1 ⁇ m to 2 ⁇ m. If the thickness of the dense barrier layer 153 is 0.01 ⁇ m or more, a uniform layer is formed, and the corrosion resistance of the metal substrate can be effectively improved.
  • the thickness of the dense barrier layer 153 is 10 ⁇ m or less, an increase in the film stress of the dense barrier layer can be suppressed, resulting in a decrease in film followability to the intermediate layer and the metal substrate, and the occurrence of peeling / cracking associated therewith. Can be prevented.
  • the ratio (coverage) of the area where the metal base material 152 is covered with the dense barrier layer 153 is 100%.
  • a coverage may be less than 100%.
  • the coverage of the metal substrate 152 by the dense barrier layer 153 is preferably 60% or more, more preferably 80 to 100%, still more preferably 90 to 100%, and most preferably 100%.
  • the intermediate layer 154 is disposed on the dense barrier layer 153.
  • the intermediate layer 154 has a function of improving the adhesion between the dense barrier layer 153 and the conductive thin film layer 155 and a function of preventing elution of ions from the metal substrate 152.
  • the function and effect obtained by installing the intermediate layer 154 is remarkably exhibited when the dense barrier layer 153 is made of the above-described metal or the like.
  • the intensity ratio between the D band peak intensity (I D ) and the G band peak intensity (I G ) measured by Raman scattering spectroscopic analysis in which the conductive thin film layer 155 contains conductive carbon.
  • the conductive carbon layer has a large R (I D / I G ), for example, when the R value exceeds 2.0, the adhesive effect with the conductive thin film layer 155 is remarkable by providing the intermediate layer 154.
  • the material constituting the intermediate layer 154 is not particularly limited as long as it provides the above-mentioned adhesion, but the same material as the intermediate layer 32 of the first embodiment can be used.
  • the thickness of the intermediate layer 154 is not particularly limited, but can be the same thickness as the intermediate layer 32 of the first embodiment.
  • the structure of the intermediate layer 154 is not particularly limited, but can be a columnar structure similar to the intermediate layer 32 of the first embodiment.
  • the thermal expansion coefficient of the material constituting the intermediate layer 154 is equal to or lower than the thermal expansion coefficient of the material constituting the dense barrier layer 153, adhesion between the intermediate layer and the dense barrier layer is improved. Can do. However, in such a form, the adhesion between the intermediate layer 154 and the conductive thin film layer 155 may be reduced. Similarly, if the thermal expansion coefficient of the intermediate layer 154 is equal to or less than the thermal expansion coefficient of the conductive thin film layer 155, the adhesion between the intermediate layer 154 and the conductive thin film layer 155 may decrease.
  • the coefficient of thermal expansion ( ⁇ sub ) of the material constituting the metal substrate, the coefficient of thermal expansion ( ⁇ den ) of the material constituting the dense barrier layer, and the coefficient of thermal expansion ( ⁇ of the material constituting the intermediate layer) mid ) and the coefficient of thermal expansion of the material constituting the conductive thin film layer ( ⁇ c ) preferably satisfy the following relationship.
  • the conductive thin film layer 155 is disposed on the intermediate layer 154.
  • the conductive thin film layer 155 include a metal thin film layer and a conductive carbon layer formed from carbon.
  • a material which comprises a metal thin film layer copper (Cu), gold (Au), silver (Ag), platinum (Pt), palladium (Pd), etc. are mentioned.
  • the conductive carbon layer is a layer containing conductive carbon. Of these, a conductive carbon layer is preferred. The presence of the conductive carbon layer improves the corrosion resistance as compared with the case where the conductive carbon layer is not included while ensuring the conductivity of the conductive member constituting the separator 5A. As such a conductive carbon layer, the conductive carbon layer 33 of the first embodiment can be used.
  • a dense barrier layer is formed on a metal substrate by plating, spraying, CVD or coating [step (1)].
  • an intermediate layer is formed on the dense barrier layer by sputtering or ion plating [Step (2)].
  • a conductive thin film layer is formed on the intermediate layer by a sputtering method or an ion plating method [step (3)].
  • Step (1) First, a metal plate such as a stainless plate or an aluminum plate having a desired thickness is prepared as a metal substrate. Next, as in the first embodiment, the surface of the prepared metal substrate is degreased and cleaned using an appropriate solvent. Subsequently, the oxide film formed on the surface (both sides) of the metal substrate is removed. As a method for removing the oxide film, the same method as in the first embodiment is used.
  • a dense barrier layer is formed on the surface of the metal substrate subjected to the above treatment.
  • the method for forming the dense barrier layer is not particularly limited as long as the crystal orientation is lowered as described above, but plating, thermal spraying, CVD (Chemical Vapor Deposition), and coating are used.
  • the dense barrier layer is formed on the surface of the metal substrate by plating.
  • the plating conditions are not particularly limited as long as the above-described dense barrier layer can be formed.
  • Known conditions are used, and vary depending on the type and amount of the constituent material of the dense barrier layer used.
  • Cr plating treatment conditions are a current density of 3 to 10 A / dm 2 , a bath temperature of 20 to 60 ° C., and an electrodeposition time of 30 to 120 minutes. Under such conditions, the dense barrier layer as described above can be easily formed.
  • a dense barrier layer having a spherical or granular structure (surface convex portion) with low crystal orientation can be formed on the metal substrate.
  • the size of the spherical / granular structure of the dense barrier layer is preferably fine enough not to pass water molecules.
  • the average crystallite diameter of the spherical / granular structure of the dense barrier layer is preferably 10 nm to 30 nm, more preferably 10 nm to 20 nm. With such a size, the penetration of water molecules can be effectively suppressed.
  • the “average crystallite diameter of the spherical / granular structure of the dense barrier layer” is calculated using the Scherrer equation from the half-value width of the peak intensity ratio by X-ray diffraction.
  • Step (2) Next, an intermediate layer is formed on the dense barrier layer formed in the step (1).
  • the formation method of the intermediate layer is not particularly limited as long as the crystal orientation is high to some extent as described above, but the sputtering method and the ion plating method are used as in the first embodiment. .
  • a sputtering method is particularly preferable.
  • the boundary portion between the dense barrier layer and the intermediate layer is a dense and low crystallinity portion derived from the dense barrier layer
  • the boundary portion between the dense barrier layer and the intermediate layer is a dense and low crystallinity portion derived from the dense barrier layer
  • an intermediate layer having a columnar structure having higher crystal orientation than the dense barrier layer can be formed on the dense barrier layer.
  • the size of the columnar structure of the intermediate layer is not particularly limited, but it may be larger than the size of the spherical / granular structure of the dense barrier layer in consideration of adhesion to the dense barrier layer and the conductive thin film layer. preferable.
  • the average size (average thickness) of the columnar crystals in the intermediate layer is preferably 10 nm to 100 nm, more preferably 30 nm to 100 nm. With such a size, sufficient adhesion with the dense barrier layer and the conductive thin film layer can be achieved.
  • the “average size of the columnar structure of the intermediate layer” is calculated by image analysis of the cross section of the intermediate layer with an SEM.
  • Step (3) Next, a conductive thin film layer is formed on the intermediate layer formed in the step (2).
  • the conductive thin film layer is made of conductive carbon
  • the conductive thin film layer can be formed by the same method as in the first embodiment.
  • a conductive member in which the metal base 152, the dense barrier layer 153, the intermediate layer 154, and the conductive thin film layer 155 are sequentially formed can be manufactured.
  • the dense barrier layer 153, the intermediate layer 154, and the conductive thin film layer 155 are formed only on one side of the metal base material 152, but a conductive member in which the above layers are formed on both sides of the metal base material 152.
  • the same method as described above may be applied to the other surface of the metal substrate 152.
  • the conductive member of the present embodiment can be used for various applications as in the first embodiment.
  • a typical example is a PEFC separator 5A.
  • the conductive member When the conductive member is used for a PEFC separator, it may be used for at least one of an anode and a cathode. However, considering the generation of a large amount of water on the cathode side, it is preferable to use the conductive member as at least a cathode separator. More preferably, the conductive member of this embodiment is used for both the cathode separator and the anode separator. In the present embodiment, the dense barrier layer does not need to be covered over the entire surface of the metal substrate for both separators.
  • the coverage with the cathode separator is preferably equal to or higher than the coverage with the anode separator.
  • the relationship of the coverage of the metal substrate with the dense barrier layer on the anode separator side relative to the cathode separator side is preferably 60 to 100 on the anode side, assuming that the coverage on the cathode separator side is 100. More preferably, it is 80-100.
  • the dense barrier layer does not necessarily have to be formed over the entire surface of the metal substrate (with a coverage of 100%).
  • the dense barrier layer is formed on the metal substrate so that the in-plane distribution of each separator is continuously or divided into two or more regions so that the downstream side of the gas flow direction has a higher coverage. It is formed. This is due to the fact that a large amount of water is generated at the cathode and anode at the downstream side with respect to the gas flow direction.
  • a dense barrier layer is formed on the metal substrate according to the amount of water generated, and the invasion of water molecules is more effectively suppressed, and the conductivity and corrosion resistance of the conductive member are reduced. Reduction can be suppressed more effectively.
  • the conductive member of this embodiment can be used as a separator for various fuel cells such as PAFC, MCFC, SOFC, or AFC in addition to PEFC, similarly to the conductive member of the first embodiment.
  • fuel cell separator it can be used for other fuel cell components (current collector plate, bus bar, gas diffusion base, MEA), electronic component contacts, and the like.
  • the conductive member of this embodiment can be used in a wet environment and an energized environment. When used in such an environment, the effect of the present invention of achieving both conductivity and corrosion resistance is remarkably exhibited.
  • the pretreated aluminum plate was subjected to chrome plating in a sergeant bath to form a dense barrier layer.
  • the plating treatment conditions were a current density of 4 A / dm 2 , a bath temperature of 35 ° C., and an electrodeposition time of 1 hour, whereby a dense barrier layer (Cr plating) made of Cr having a thickness of 2 ⁇ m was formed.
  • the average crystallite diameter of the dense barrier layer thus formed was measured by the Scherre method in the X-ray diffraction method and found to be 15 nm.
  • the product made by Mac Science Co., Ltd. was used as an X-ray diffraction apparatus.
  • the cross section was subjected to image analysis by SEM, and the area ratio occupied by Cr plating was measured to obtain the porosity. As a result, the porosity was 1% or less.
  • an intermediate layer was formed on the aluminum plate by UBMS while applying a negative bias voltage of 50 V to the aluminum plate using Cr as a target.
  • the thickness of the intermediate layer made of Cr was 0.2 ⁇ m.
  • the average crystallite diameter of the thus formed intermediate layer was measured in the same manner as in Reference Example II-1, and found to be 30 nm. Further, when the porosity of this intermediate layer was determined in the same manner as in Reference Example II-1, it was 7%.
  • the dense barrier layer formed in Reference Example II-1 was more void than the intermediate layer formed in this Example. It can be seen that the rate is low.
  • the degree of crystal orientation crystal orientation
  • the dense barrier layer formed in Reference Example II-1 has a crystal orientation higher than that of the intermediate layer formed in this example. Is considered low. It is also considered that the degree of crystal orientation of each layer can be easily adjusted by adjusting the average crystallite size.
  • FIG. 22A Reference Example II-1
  • FIG. 22B Reference Example II.
  • 22A and 22B that the dense barrier layer of Reference Example II-1 has a granular structure, while the intermediate layer of Reference Example II-2 has a columnar structure. Also from this figure, it can be seen that the dense barrier layer of Reference Example II-1 is denser than the intermediate layer of Reference Example II-2, and this result agrees with the result of the porosity described above. Is.
  • FIG. 23C Reference Example II-1 and II-2
  • FIG. 23D Reference Example II-2
  • FIG. 23C it can be confirmed that granular or spherical chromium particles 153a are densely aggregated in the dense barrier layer, and the porosity of the dense barrier layer 153 is extremely low. Further, it can be seen that the crystal axes of the chromium particles 153a are present in various directions, and the crystal orientation is low.
  • FIG. 23C shows that granular or spherical chromium particles 153a are densely aggregated in the dense barrier layer, and the porosity of the dense barrier layer 153 is extremely low.
  • the crystal axes of the chromium particles 153a are present in various directions, and the crystal orientation is low.
  • Example II-1 In the same manner as described in Reference Example II-1, a dense barrier layer (Cr plating, average crystallite diameter: 15 nm) made of Cr having a thickness of 2 ⁇ m was formed on both surfaces of the metal substrate. Next, in the same manner as described in Reference Example II-2, while applying a negative bias voltage (50 V) using Cr as a target to the dense barrier layer on one surface by the UBMS method, An intermediate layer (average crystallite diameter: 30 nm) made of Cr having a thickness of 2 ⁇ m was formed. Further, the same operation was repeated to form an intermediate layer made of Cr having a thickness of 0.2 ⁇ m on the dense barrier layer on the other surface.
  • a negative bias voltage 50 V
  • a laminate of 5 intermediate layers was prepared.
  • the laminate was cut into a size of 30 mm ⁇ 30 mm, and the side surface was masked with a silicon material to prepare a sample (II-1).
  • Example II-2 In the same manner as described in Reference Example II-1, a dense barrier layer (Cr plating, average crystallite diameter: 15 nm) made of Cr having a thickness of 2 ⁇ m was formed on one surface of the metal substrate. Next, in the same manner as described in Reference Example II-2, a negative bias voltage (50 V) is applied to the formed dense barrier layer by the UBMS method while applying a negative bias voltage (50 V). An intermediate layer (average crystallite diameter: 30 nm) made of Cr having a thickness of 2 ⁇ m was formed.
  • a conductive thin film layer having a thickness of 0.2 ⁇ m was formed on the intermediate layer by applying a negative bias voltage having a magnitude of 100 V to the intermediate layer, using solid graphite as a target, by the UBMS method.
  • a negative bias voltage having a magnitude of 100 V was applied to the intermediate layer, using solid graphite as a target, by the UBMS method.
  • FIG. 24 shows the result of image analysis of the cross section of the conductive member by TEM. From FIG. 24, in the conductive member of this embodiment, the dense barrier layer is formed in a granular structure, whereas the intermediate layer is formed in a columnar structure, and the dense barrier layer is more in comparison with the intermediate layer. It turns out that it is precise. This result is consistent with the porosity result.
  • the conductive member (conductive structure) of this embodiment is formed by laminating a metal base material, an intermediate layer, and a conductive carbon layer in this order. And it has the electroconductive reinforcement layer containing electroconductive particle between the said metal base material and an intermediate
  • conductive particles exist between the metal substrate and the intermediate layer. Therefore, even when the oxide film resulting from the oxidation of the metal substrate or the intermediate layer is formed, the conductive particles can form a conductive path and maintain conductivity.
  • the conductive reinforcing layer has excellent corrosion resistance as well as improved conductivity between layers caused by suppressing an increase in resistance value. Therefore, the conductive member of this embodiment can achieve both excellent conductivity and corrosion resistance. For this reason, the fuel cell using the said electrically-conductive member as a separator can exhibit the outstanding durability, fully ensuring the outstanding electroconductivity of a metal separator.
  • the polymer electrolyte fuel cell (PEFC) according to this embodiment also has the same basic configuration as the PEFC according to the first embodiment. Specifically, as shown in FIG. 1, the PEFC has a solid polymer electrolyte membrane 2 and a pair of catalyst layers 3 (an anode catalyst layer 3a and a cathode catalyst layer 3b) that sandwich the membrane. The laminate of the solid polymer electrolyte membrane 2 and the catalyst layers (3a, 3b) is further sandwiched between a pair of gas diffusion layers (GDL) 4 (anode gas diffusion layer 4a and cathode gas diffusion layer 4b). .
  • GDL gas diffusion layers
  • the solid polymer electrolyte membrane 2, the pair of catalyst layers 3 (3a, 3b), and the pair of gas diffusion layers 4 (4a, 4b) constitute a membrane electrode assembly (MEA) 9 in a stacked state.
  • MEA membrane electrode assembly
  • the MEA 9 is further sandwiched between a pair of separators 5 (an anode separator 5a and a cathode separator 5b).
  • FIG. 25 is a cross-sectional view showing a configuration of a separator 5B which is a conductive member of the present embodiment.
  • the separator 5 ⁇ / b> B includes a metal base 252, an intermediate layer 256, and a conductive carbon layer 254.
  • a conductive reinforcing layer 255 is interposed between the metal base 252 and the intermediate layer 256.
  • the separator 5B is arranged so that the conductive carbon layer 254 is located on the MEA 9 side.
  • each component of the separator 5B of this embodiment is explained in full detail.
  • the metal base 252 is a main layer of a conductive member that constitutes the separator 5B, and contributes to ensuring conductivity and mechanical strength. And the metal base material 252 which concerns on this embodiment can use the thing similar to the metal base material 31 of 1st embodiment.
  • an oxide film may be formed on at least one surface of the metal substrate 252.
  • the oxide film may be formed naturally by leaving the metal substrate in the air, or may be an artificially oxidized metal substrate in an oxidizing atmosphere (gas, solution).
  • a metal base material is formed from stainless steel, it contains Cr 2 O 3 , NiO, and Fe 2 O 3 .
  • the metal substrate is made of aluminum, Al 2 O 3 is included.
  • the metal substrate is made of iron, it contains Fe 2 O 3 .
  • the metal substrate is formed from titanium, including TiO 2.
  • the conductive reinforcing layer 255 is a layer containing conductive particles, and is disposed on the metal substrate 252. Due to the presence of this layer, sufficient conductivity is ensured even when an oxide film is formed on the metal substrate or in the intermediate layer described later. Therefore, due to the arrangement of the conductive reinforcing layer 255, the conductive member constituting the separator 5 is more conductive than the conductive member having only the metal substrate 252, the intermediate layer 256, and the conductive carbon layer 254 while ensuring corrosion resistance. Can be improved.
  • the conductive particles are not particularly limited as long as they are conductive and do not form oxides. Specifically, it is preferably at least one selected from the group consisting of noble metal elements, alloys containing noble metal elements, and carbon. In such a case, even when acidic water penetrates into the layer, the conductive particles do not form an oxide film, so that good conductivity can be maintained.
  • the noble metal element is selected from the group consisting of gold (Au), silver (Ag), platinum (Pt), palladium (Pd), rhodium (Rh), iridium (Ir), ruthenium (Ru) and osmium (Os). Preferably, at least one of these is preferred.
  • the alloy containing a noble metal examples include a gold-cobalt alloy (Au—Co), a gold-nickel alloy (Au—Ni), a palladium-nickel alloy (Pd—Ni), and the like.
  • Preferred examples of carbon include at least one selected from the group consisting of graphite, carbon black, amorphous carbon, activated carbon, coke, and glassy carbon. Of these, relatively inexpensive graphite is preferable.
  • the alloy containing a noble metal element, or carbon you may use individually by 1 type, and may mix and use 2 or more types.
  • electroconductive particle contains the material different from the material which comprises an intermediate
  • the average particle diameter of the conductive particles is preferably equal to or greater than the thickness of the oxide film formed on the surface of the metal substrate or intermediate layer.
  • the thickness of the oxide film may be measured in advance, and the average particle diameter of the conductive particles may be equal to or greater than the thickness of the oxide film.
  • the thickness of the oxide film formed on the surface of the material is determined by Auger electron. The method of measuring by spectroscopy (AES) etc. is mentioned.
  • AES spectroscopy
  • the thickness of the oxide film may be measured for a material immersed in acidic water for a certain period of time.
  • FIG. 26 is a drawing showing the results of measuring the element concentration of a metal substrate (SUS316L) immersed in an aqueous sulfuric acid solution at 80 ° C. and pH 4 for 100 hours using Auger electron spectroscopy.
  • a metal substrate SUS316L
  • oxygen (O ′) derived from the surface oxide is present at a depth of about 10 nm from the surface layer. Therefore, under such conditions, the average particle diameter of the conductive particles is preferably 10 nm or more, more preferably 10 nm to 100 nm, and even more preferably 10 nm to 20 nm.
  • the acidic atmosphere in a battery changes with electric power generation conditions, it is desirable to perform the prior evaluation of the thickness of a surface oxide on the conditions which simulated the internal environment in a battery according to electric power generation conditions.
  • the thickness of the oxide film formed on a typical metal base material is about 0.001 nm to 0.1 nm for SUS and about 0.001 nm to 1 nm for Al. Therefore, the average particle diameter of the conductive particles is preferably 0.01 nm to 100 nm, more preferably 1 nm to 100 nm, and further preferably 10 nm to 100 nm. If the thickness is 0.01 nm or more, the effect of the present embodiment can be obtained. However, if the thickness is 10 nm or more, the thickness of the oxide film formed by almost all the base metal or the material constituting the intermediate layer is increased. Therefore, the contact between the conductive particles or between the conductive particles and the metal substrate and the intermediate layer is secured, and the conductivity is improved.
  • the “particle diameter” means the maximum distance among the distances between any two points on the particle outline. Further, as the value of “average particle diameter”, unless otherwise specified, particles observed in several to several tens of fields using an observation means such as a scanning electron microscope (SEM) or a transmission electron microscope (TEM) The value calculated as the average value of the particle diameters of the particles shall be adopted.
  • SEM scanning electron microscope
  • TEM transmission electron microscope
  • the coverage of the metal substrate with the conductive particles is preferably 50% to 100%, more preferably 65% to 100%, still more preferably 70% to 100%, and particularly preferably 80% to 95%. It is. If it is 50% or more, sufficient electroconductivity can be ensured and the raise of the contact resistance of an electroconductive member can be suppressed. From the viewpoint of improving conductivity, the coverage is preferably as large as possible, and is preferably 100% (complete coverage). However, the amount of conductive particles increases as the coverage increases. Since noble metal elements which are typical conductive particles are expensive, considering the cost, it is preferable that the coverage is small as long as conductivity is ensured.
  • the “covering ratio of the metal substrate with the conductive particles” means the ratio of the area of the conductive particles in the conductive reinforcing layer overlapping the metal substrate 252 when the conductive member (separator 5) is viewed from the stacking direction. Means.
  • the coverage for example, the in-plane distribution of elements of conductive particles obtained by Auger electron spectroscopy may be image-processed, and the coverage (base material exposure rate) may be calculated from the area ratio.
  • FIG. 27 shows the relationship between the coverage of the metal substrate by the conductive particles and the contact resistance in the member in which the surface of the metal substrate on which the oxide film is formed is coated with the conductive particles (Au).
  • the graph shown by the dotted line in FIG. 27 shows the relationship between the coverage and the contact resistance in a dense state with a lot of oxide film on the surface of the metal substrate, and the graph shown by the solid line shows the coverage in a state with little oxide film.
  • the contact resistance It can be seen from FIG. 27 that the contact resistance tends to increase as the coverage decreases. Furthermore, although depending on the density of the oxide film, it is confirmed that the contact resistance can be significantly reduced even if the state of the oxide film is different if the coverage is 50% or more.
  • the conductive reinforcing layer may contain other materials in addition to the conductive particles. By including other materials, not only the conductivity between layers is improved, but also the corrosion resistance is excellent. Further, when an expensive noble metal element is used as the conductive particles, the amount used can be reduced, which is advantageous in terms of cost.
  • Other materials include Group 4 metals (Ti, Zr, Hf), Group 5 metals (V, Nb, Ta), Group 6 metals (Cr, Mo, W), etc. Metals; semimetals such as Si and B; alloys, carbides and nitrides of the above metals.
  • metals with low ion elution such as chromium (Cr), tungsten (W), titanium (Ti), molybdenum (Mo), niobium (Nb) or hafnium (Hf), or nitrides, carbides or carbonitrides thereof.
  • the product is preferably used. More preferably, Cr or Ti, or a carbide or nitride thereof is used.
  • Cr or Ti, or a carbide or nitride thereof is used.
  • the corrosion resistance of the conductive member can be significantly improved.
  • the content of the conductive particles in the conductive reinforcing layer 255 is not particularly limited, and may be appropriately adjusted so that the coverage of the metal substrate with the conductive particles becomes the above desired value.
  • the material constituting the conductive reinforcing layer other than the conductive particles is the thermal expansion coefficient of the material constituting the intermediate layer (metal, metal carbide or metal nitride constituting the intermediate layer) described in detail below. It is preferable that the thermal expansion coefficient be exceeded.
  • the conductive carbon layer is difficult to thermally expand, and the metal substrate is easily thermally expanded.
  • the metal base material, the conductive reinforcing layer, the intermediate layer, and the conductive thin film layer are selected by selecting the materials constituting the conductive reinforcing layer and the intermediate layer so that the thermal expansion coefficient is as described above. A difference in expansion and contraction due to heat can be suppressed, and peeling of each layer can be prevented. In such a case, the adhesion between the conductive reinforcing layer and the intermediate layer can also be improved.
  • the coverage of the conductive particles in the conductive reinforcing layer with respect to the metal substrate increases from the upstream to the downstream in the gas flow direction.
  • the coverage of the conductive particles is the lowest at the upstream regardless of the anode and cathode, and is about 50%, and the downstream of the severe corrosive environment increases the coverage as necessary in consideration of power generation conditions and the like. Is preferred.
  • the concentration gradient in the in-plane direction of the conductive reinforcing layer may continuously increase with respect to the gas flow direction. Further, the density gradient may be increased stepwise by providing a plurality of divided regions having different densities. However, the conductive particles may be uniformly dispersed over the entire region.
  • FIG. 28 is a schematic cross-sectional view of a conductive member including conductive particles and a columnar material according to the present embodiment.
  • the “columnar material” refers to a material having a columnar structure with high crystal orientation. “Crystal orientation” is the same as that described in the dense barrier layer column in the second embodiment.
  • the conductive reinforcing layer 255 includes a columnar material 258 having a columnar structure arranged in the thickness direction of the conductive member in addition to the conductive particles 257.
  • the conductive particles 257 are present on the surface of the columnar material 258 of the conductive reinforcing layer and on the interface between the metal substrate 252 and the conductive reinforcing layer 255.
  • the conductive reinforcing layer includes a columnar material having a large number of columnar structures at the nano level, voids between the columnar structures become a flow path of acidic water, and an oxide film is formed on the surface of the columnar structure and the surface of the base metal.
  • Cheap when an intermediate layer, which will be described later, is made of a columnar material having a columnar structure arranged in the thickness direction of the conductive member, the gap between the columns forms a passage for acidic water, and the formation of an oxide film tends to proceed. And since such an oxide film shows insulation, there existed a problem that the electroconductivity of a separator was reduced and the contact resistance as a separator increased.
  • the conductive reinforcing layer of this embodiment since conductive particles are present on the surface of the columnar material, a conductive path between the columnar shapes is formed, and sufficient in-plane conductivity can be secured. Furthermore, in this embodiment, since conductive particles exist also at the interface between the metal substrate and the conductive reinforcing layer, an increase in resistance at the metal substrate interface can be suppressed. Therefore, even if an oxide film is formed, a decrease in conductivity can be effectively suppressed. Such a columnar material is easily generated when a film is formed using a sputtering method.
  • the conductive reinforcing layer and the intermediate layer have a columnar structure arranged in a large number in the thickness direction of the conductive member.
  • the structure of the intermediate layer is not limited to the columnar structure, and various other types. Can take form.
  • distribution form of electroconductive particle is not necessarily restricted to said form, The other dispersion
  • a structure in which conductive particles and other materials are laminated by forming layers may be used as another dispersion form.
  • a structure in which conductive particles and other materials are laminated by forming layers may be used.
  • the structure of such a conductive reinforcing layer or intermediate layer can be confirmed by SEM-EDX (scanning electron microscope-energy dispersive X-ray analyzer), TEM, or the like.
  • the thickness of the conductive reinforcing layer 255 is not particularly limited, and the thinner one is preferable as long as an increase in resistance due to the formation of an oxide film at the interface of the metal substrate can be suppressed.
  • the thickness is preferably equal to or greater than the thickness of a region where an oxide film is formed on the surface of the metal substrate.
  • the thickness of the conductive reinforcing layer 255 is preferably thinner than the thickness of the intermediate layer described later. In this case, the effect of improving the adhesion of the intermediate layer and the effect of improving the conductivity of the conductive reinforcing layer are exhibited, and space saving is possible.
  • the conductive reinforcing layer may be present on at least one surface of the metal base material, but may be present on both surfaces of the metal base material from the viewpoint of further achieving the desired effect in the present embodiment.
  • middle layer and a conductive carbon layer will be further provided on the surface of each conductive reinforcement layer.
  • the conductive reinforcing layer exists between the conductive carbon layer to be disposed on the MEA side and the metal substrate. It is preferable.
  • the conductive reinforcing layer may have a laminated structure including not only one layer but also a plurality of layers.
  • the intermediate layer 256 is a layer disposed on the conductive reinforcement layer 255, and improves the adhesion between the metal substrate 252 and the conductive reinforcement layer 255, and the elution of ions from the metal substrate 252. It has a function of preventing. In particular, the effect of the installation of the intermediate layer 256 is remarkably exhibited when the conductive reinforcing layer 255 is made of the above metal or an alloy thereof.
  • the conductive carbon layer 254 contains conductive carbon, and the D band peak intensity (I D ) and G band peak intensity (I G ) measured by Raman scattering spectroscopic analysis. When the intensity ratio R (I D / I G ) is large (for example, the R value exceeds 2.0), the adhesive effect with the conductive reinforcing layer 255 is remarkably exhibited by providing the intermediate layer 256. .
  • the material constituting the intermediate layer 256 is not particularly limited as long as it provides the above-mentioned adhesion, but the same material as that of the intermediate layer 32 of the first embodiment can be used.
  • the thickness of the intermediate layer 256 is not particularly limited, but can be the same thickness as the intermediate layer 32 of the first embodiment.
  • the structure of the intermediate layer 256 is not particularly limited, but can be a columnar structure similar to the intermediate layer 32 of the first embodiment.
  • the thermal expansion coefficient of the material constituting the intermediate layer 256 is equal to or lower than the thermal expansion coefficient of the material constituting the conductive reinforcing layer 255, the adhesion between the intermediate layer and the conductive reinforcing layer is improved. can do. Further, when the thermal expansion coefficient of the intermediate layer 256 is equal to or higher than the thermal expansion coefficient of the conductive carbon layer 254, adhesion between the intermediate layer 256 and the conductive reinforcing layer 255 can be improved.
  • the coefficient of thermal expansion ( ⁇ sub ) of the material constituting the metal substrate, the coefficient of thermal expansion ( ⁇ rei ) of the material constituting the conductive reinforcing layer, and the coefficient of thermal expansion of the material constituting the intermediate layer ( ⁇ mid ) and the coefficient of thermal expansion ( ⁇ c ) of the material constituting the conductive thin film layer preferably satisfy the following relationship.
  • the conductive carbon layer 254 is a layer that is disposed on the intermediate layer 256 and contains conductive carbon. By the presence of this layer, the corrosion resistance is improved as compared with the case of only the metal substrate 252 while ensuring the conductivity of the conductive member (separator) 5. As such a conductive carbon layer 254, the conductive carbon layer 33 of the first embodiment can be used.
  • a stainless steel plate having a desired thickness is prepared as a metal substrate.
  • the surface of the prepared metal substrate is degreased and cleaned using an appropriate solvent.
  • the oxide film formed on the surface (both sides) of the metal substrate is removed.
  • the same method as in the first embodiment is used.
  • a step of forming a conductive reinforcing layer on the surface of the metal substrate subjected to the above-described treatment is performed.
  • the above-described constituent material of the conductive reinforcing layer conductive particles and other materials as necessary
  • a layer containing conductive particles is laminated on a metal substrate at the atomic level, thereby providing conductivity.
  • a reinforcing layer can be formed.
  • Suitable methods for laminating the conductive particles and other materials include PVD methods such as a plating method, sputtering method or ion plating method, or ion beam evaporation methods such as FCVA method.
  • Examples of the sputtering method include magnetron sputtering, UBMS, and dual magnetron sputtering.
  • Examples of the ion plating method include an arc ion plating method.
  • it is preferable to use sputtering method and an ion plating method and it is especially preferable to use sputtering method. According to such a method, film formation can be performed at a relatively low temperature, and damage to the metal base material as a base can be minimized.
  • the film quality of the deposited layer can be controlled by controlling the bias voltage and the like.
  • the dispersion form of the conductive particles can be controlled by adjusting the sputtering conditions such as the sputtering rate.
  • the coverage and particle diameter of the conductive particles can be set to a desired range by controlling the relationship between the sputtering time and the dispersion amount in advance.
  • a step of forming an intermediate layer and a conductive carbon layer on the surface of the conductive reinforcing layer is performed.
  • a method for forming the intermediate layer and the conductive carbon layer the same method as described above for the formation of the conductive reinforcing layer can be used.
  • a sputtering method and an ion plating method are used. More preferably, a sputtering method is used, and an unbalanced magnetron sputtering method is particularly preferably used.
  • the conductive carbon layer is formed by such a method, in addition to the above-described advantages, a carbon layer having a low hydrogen content can be formed. As a result, the ratio of bonds between carbon atoms (sp 2 hybrid carbon) can be increased, and excellent conductivity can be achieved.
  • the boundary between the conductive reinforcing layer and the intermediate layer is derived from the conductive reinforcing layer and the intermediate layer. May have a structure that coexists. Even if such a coexistence portion exists, the effect of the present invention can be sufficiently achieved if the conductive reinforcing layer and the intermediate layer are arranged with the above-described thickness.
  • each layer when forming each layer by sputtering method, it is good to apply a negative bias voltage with respect to a metal base material at the time of sputtering.
  • a layer having a structure in which constituent particles and graphite clusters of each layer are densely assembled can be formed by the ion irradiation effect. Since such a layer exhibits excellent conductivity, it is possible to provide a conductive member (separator) having a low contact resistance with another member (for example, MEA).
  • the magnitude (absolute value) of the negative bias voltage to be applied is not particularly limited, and a voltage capable of forming each layer is adopted.
  • the magnitude of the applied voltage is preferably 50 to 500V, more preferably 100 to 300V.
  • specific forms, such as other conditions at the time of film-forming, are not restrict
  • a conductive member in which the conductive reinforcing layer 255, the intermediate layer 256, and the conductive carbon layer 254 are formed on one main surface of the metal base 252 can be manufactured. And in order to manufacture the electrically-conductive member in which the electroconductive reinforcement layer 255 was formed in both surfaces of the metal base material 252, it is electroconductive by the method similar to the above-mentioned with respect to the other main surface of the metal base material 252.
  • the reinforcing layer 255 may be formed.
  • the conductive member of the present embodiment can be used for various applications as in the first embodiment.
  • a typical example is a PEFC separator 5B shown in FIG.
  • the conductive member may be applied to at least one of the anode separator 5a and the cathode separator 5c.
  • the conductive member is preferable to use the conductive member as at least a cathode separator. More preferably, the conductive member is used for both the cathode separator and the anode separator.
  • the amount of conductive particles in the conductive reinforcing layer is preferably larger in the cathode separator than in the anode separator.
  • a voltage of 0 to 1 V (vs. SHE) is generated at the cathode, and a substantially equal potential is also applied to the surface of the separator.
  • the corrosive environment is extremely severe. Therefore, in the cathode separator that requires more corrosion resistance, the effect of improving the conductivity and corrosion resistance due to the conductive particles is further exhibited.
  • the application of the conductive member of the present embodiment to a PEFC separator has been described.
  • the application of the conductive member of the present embodiment is not limited to this.
  • the conductive member of the first embodiment in addition to PEFC, it can be used as various fuel cell separators such as PAFC, MCFC, SOFC, or AFC.
  • the fuel cell separator in addition to the fuel cell separator, it is used in various applications that require both conductivity and corrosion resistance. Examples of uses other than the fuel cell separator in which the conductive member of the present embodiment is used include other fuel cell components (current collector plate, bus bar, gas diffusion base, MEA), contacts of electronic components, and the like.
  • the conductive member of this embodiment can be used in a wet environment and an energized environment. When used in such an environment, the effect of the present invention of achieving both conductivity and corrosion resistance is remarkably exhibited.
  • Example III-1 A stainless steel plate (SUS316L) was prepared as a metal substrate constituting the conductive member.
  • the stainless steel plate has a thickness of 100 ⁇ m.
  • As a pretreatment the stainless steel plate was ultrasonically cleaned in an ethanol solution for 3 minutes. Next, the cleaned stainless steel plate was placed in a vacuum chamber, and ion bombardment with Ar gas was performed to remove the oxide film on the surface.
  • the vacuum degree of the vacuum chamber was about 10 ⁇ 3 Pa, and the Ar gas pressure was about 0.1 to 1 Pa.
  • the pretreatment and ion bombardment described above were both performed on both surfaces of the stainless steel plate.
  • a conductive reinforcing layer made of Au and Cr was formed on both surfaces of the stainless steel plate by using unbalanced magnetron sputtering as a target with Au as conductive particles and Cr as another conductive reinforcing layer material.
  • the thickness of the conductive reinforcing layer was 20 nm.
  • the film forming layer forms a layer of a film forming material having a number of columnar structures.
  • the conductive reinforcing layer is formed of a surface of a layer of Cr having a columnar structure and a stainless steel plate. It was revealed that Au particles were dispersed at the interface with the (metal substrate). In the conductive reinforcing layer, the Au particle coverage (surface coverage) was 90%. The Au particle coverage was calculated by AES surface analysis and image analysis. The coverage was calculated according to AES and an image analysis method described later. In this calculation, a sample in which the film formation process was stopped immediately before the start of film formation of the conductive carbon layer prepared separately was used.
  • the conductive particle (Au) coverage can be determined by the difference in sputtering rate between Au and Cr formed simultaneously. In the case of the present embodiment, it is desirable to change the size and position of the target so that Au having a higher sputtering speed is dispersed to the minimum necessary. Furthermore, when the target conditions are determined, the coverage ratio and the layer thickness can be uniquely determined by the film formation time.
  • an intermediate layer having a columnar structure made of Cr was formed on the conductive reinforcing layers on both surfaces of the stainless steel plate using Cr as a target by the UBMS method.
  • the intermediate layer was formed while applying a negative bias voltage of 50 V to the stainless steel plate.
  • the intermediate layer had a thickness of 0.2 ⁇ m.
  • a conductive carbon layer was formed on the intermediate layer formed on both surfaces of the stainless steel plate by using the UBMS method with solid graphite as a target.
  • the conductive carbon layer was formed while applying a negative bias voltage of 140 V to the stainless steel plate.
  • the thickness of the conductive carbon layer was 0.2 ⁇ m.
  • Example III-2 Sample (III-2) was produced in the same manner as in Example III-1. In addition, the electroconductive reinforcement layer whose Au coverage is 38% was formed by adjusting the film-forming time.
  • Example III-3 Sample (III-3) was produced in the same manner as in Example III-1, except that Ag was used instead of Au as the conductive particles. The Ag coverage was measured in the same manner as in Examples III-1 and III-2 and found to be 83%.
  • Sample (III-4) was produced in the same manner as in Example III-1 described above, except that the intermediate layer made of Cr was directly formed on the stainless steel plate without using conductive particles. At this time, the thickness of the intermediate layer was made equal to the sum of the thickness of the conductive reinforcing layer and the thickness of the intermediate layer in Example III-1.
  • the contact resistance in the above means the contact resistance value in the lamination direction of the conductive member, and the measurement was performed by the method described in the first embodiment. The measurement results of the contact resistance value are shown in Table 4 below.
  • the element concentration profile in the stacking direction of the conductive member was measured by AES.
  • 30 to 33 show the element distributions in the depth direction from the surface of the conductive carbon layer for the samples (III-1) to (III-4) after the corrosion resistance test was performed.
  • oxygen (O) is distributed from the surface of the metal substrate (Fe, Ni) to the intermediate region of the Cr layer, and an oxide film is formed.
  • Au or Ag conductive particles are present in the oxygen distribution region (oxide film). However, it can be seen that these conductive particles are not present in the conductive member of Reference Example III-1 (sample (III-4)).
  • the element concentration profile in the in-plane direction of the conductive member is measured by AES, and the in-plane distribution of the element of the conductive particles is image-processed to calculate the coverage of the metal substrate with the conductive particles from the area ratio. did. Table 4 shows the results.
  • the AES measurement was performed under the following conditions.
  • AES equipment name Field emission type Auger electron spectrometer PHI Model-680 Number of data points: 256 ⁇ 256 Electron beam acceleration voltage: 10 kV Coverage calculation by image processing: High-speed image processing device KS400 manufactured by Carl Zeiss Import into digital images and calculate area ratio of target elements.
  • Example III-1 (sample (III-1)) having a coverage of 50% or more is the conductive member of Example III-2 (sample (III-2) having a coverage of less than 50%. It was confirmed that the increase in contact resistance can be reduced compared to)).
  • the particle diameter is an average particle diameter observed when observed by SEM. Therefore, when the coverage is 50% or more, the particles come into contact with each other to form a layer, which makes measurement difficult. For this reason, the thickness of the layer formed from the conductive particles was measured.
  • the conductive member (conductive structure) of the first to third embodiments uses a metal substrate (metal plate) as a substrate.
  • the conductive member (conductive structure) according to the present embodiment uses a porous material as a base material, and the use thereof includes a gas diffusion layer for a fuel cell. Therefore, hereinafter, the configuration of the conductive member of the present embodiment will be described by taking the case where the conductive member is used as a gas diffusion layer as an example.
  • the gas diffusion layer includes a porous material layer and a conductive carbon layer or conductive carbon particles present on or in the surface of the porous material layer. Further, in the conductive carbon layer or conductive carbon particles, the intensity ratio of the measured from the Raman scattering spectroscopy D- band peak intensity I D and G- band peak intensity I G R (I D / I G) is 1 .3 or more. In addition, the average peak measured by rotational anisotropy measurement by Raman scattering spectroscopy of the conductive carbon layer shows a two-fold symmetrical pattern.
  • the porous material layer may include one or more selected from the group consisting of carbon fiber, metal fiber, and organic fiber.
  • the carbon fiber there is a carbon fiber that has not been graphitized but has been carbonized. Since carbon fibers that have been carbonized are less expensive than graphitized carbon fibers, they are used as strength reinforcing members for buildings. However, carbon fibers that have been carbonized are inferior in electrical conductivity compared to graphitized carbon fibers.
  • a metal fiber for example, a fiber composed of a noble metal, has a sufficiently high conductivity, but is very expensive and not practical.
  • the metal fiber comprised with an inexpensive metal the electroconductivity fall by surface oxide film formation arises. In other words, the lack of conductivity due to the oxide film is a technical problem when using metal fibers.
  • the technical principle of the present embodiment is as follows. That is, even when the porous material layer is formed of an inexpensive fiber having insufficient conductivity, a GDL applicable to a fuel cell is obtained by covering the fiber with a conductive carbon layer or conductive carbon particles. That is. That is, the GDL for a fuel cell according to the present embodiment is a GDL that realizes both high conductivity and low cost.
  • the conductive carbon in the carbon fiber constituting the porous material layer is referred to as “conductive carbon constituting the porous material layer”.
  • the conductive carbon layer or the conductive carbon particles is also simply referred to as “conductive carbon” to distinguish both conductive carbons.
  • the contact resistance between the GDL formed by disposing the conductive carbon layer or the conductive carbon particles on the porous material layer and the adjacent member is significantly reduced.
  • the arrangement of the conductive carbon layer or the conductive carbon particles makes it possible to control the pore diameter of the porous material constituting the porous material layer, thereby improving the gas and liquid water dischargeability in the fuel cell.
  • the conductive carbon layer is present on the surface of the porous material layer or is present inside the porous material layer (fibrous material). On the other hand, the conductive carbon particles are mostly present inside the porous material layer.
  • the polymer electrolyte fuel cell (PEFC) according to this embodiment also has the same basic configuration as the PEFC according to the first embodiment. Specifically, as shown in FIG. 1, an anode catalyst layer 3a and a cathode catalyst layer 3b are disposed in close contact with both surfaces of a solid polymer electrolyte membrane 2 that selectively transports hydrogen ions. Further, an anode gas diffusion layer 4a and a cathode gas diffusion layer 4b having both gas permeability and conductivity are arranged in close contact with each other on the outer surface of the catalyst layer 3 (3a, 3b). A membrane electrode assembly 9 is constituted by the gas diffusion layer 4 (4a, 4b) and the solid polymer electrolyte membrane 2.
  • Adjacent separators (5a, 5b) and gas diffusion layers (4a, 4b) constitute conductive members (8a, 8b).
  • FIG. 34 is a cross-sectional view showing a schematic configuration of the gas diffusion layer according to the present embodiment.
  • the gas diffusion layer 351 includes a porous material layer 352 and a conductive carbon layer 354 as conductors.
  • An intermediate layer 356 is interposed between these layers, although not essential.
  • the cross-sectional view of the gas diffusion layer in FIG. 34 shows a structure in which an intermediate layer and a conductive carbon layer are laminated on the porous material layer.
  • the present embodiment is not limited to this structure, and there may be a structure in which an intermediate layer and a conductive carbon layer are “laminated” inside a porous material layer composed of fibers.
  • “lamination” in the present embodiment is not limited to a layer stacked on (or below) a certain layer, but may also mean a layer configured inside a certain layer.
  • one gas diffusion layer having both “laminated” forms as well as either “laminated” form may be used.
  • FIG. 34 also shows a hydrophilic layer 358, which will be described later.
  • the separators (5a, 5b) are arranged so that the conductive carbon layer 354 is located on the MEA 9 side.
  • each component of GDL for fuel cells is explained in full detail.
  • the porous material layer 352 is basically composed of a sheet-like porous material. And it is preferable that the porous material layer 352 contains 1 or more types selected from the group which consists of carbon fiber, a metal fiber, and an organic fiber. In this case, since the fibers are fused to each other in the firing step during the production of the porous material layer, the electrical resistance at the interface between them can be reduced. In other words, in such a case, there is an advantage that the conductivity is significantly increased by the fusion of the fibers.
  • FIG. 35 is a schematic view microscopically showing the surface of the porous material layer.
  • the conductive carbon layer 354 can be formed by a sputtering method.
  • the target conductive carbon
  • the conductive carbon layer or the conductive carbon particles is deposited only on the fiber surface exposed to the sputtering direction. Therefore, by changing the angle of the fiber substrate itself, in other words, by appropriately adjusting the pore diameter, the conductive carbon layer or the conductive carbon particles can be disposed on a wider surface among the surfaces.
  • the porous material layer 352 made of carbon fiber or the like is in a state where a large number of fibers (carbon fibers (CF) 353) are overlapped.
  • the conductive carbon layer 354 is deposited on the porous material layer 352 by sputtering, the target is sputtered onto the main surface of the porous material layer 352 as shown by the arrows in FIG. That is, the conductive carbon layer is formed not only on the outermost surface of the porous material layer but also in the vicinity thereof (portion exposed on the surface of the porous material layer).
  • the conductive carbon layer has not only the form laminated on the surface of the porous material layer as shown in FIG. 34, but also the form existing only in the porous material layer and the surface of the porous material layer. Forms present both on the top as well as in the porous material layer may also be employed.
  • the fiber diameter as the positional relationship between the fibers constituting the porous material layer, it is possible to realize both improvement in conductivity and prevention of an increase in pressure loss. Specifically, the larger the fiber diameter, the larger the voids in the fiber, but the number of contacts per fiber decreases. For this reason, the conductivity is lowered, but an increase in pressure loss can be prevented. On the other hand, the smaller the fiber diameter, the smaller the voids in the fiber, but the number of contacts per fiber increases. Therefore, the conductivity increases, but the pressure loss increases. Therefore, it is preferable to adjust the fiber diameter to an appropriate range.
  • the “carbon fiber” in the present embodiment means a fiber obtained by firing a raw material fiber in an inert atmosphere at a temperature of 1000 ° C. or higher.
  • Examples of such carbon fibers include, but are not limited to, polyacrylonitrile (PAN) based carbon fibers, pitch based carbon fibers, phenol based carbon fibers, and vapor grown carbon fibers.
  • PAN polyacrylonitrile
  • the PAN-based carbon fiber is a fiber made of synthetic fiber whose main component is PAN.
  • the pitch-based carbon fiber is a fiber made from petroleum, coal, synthetic pitch or the like.
  • the preferable range of the average fiber diameter of the carbon fiber varies depending on the specifications of the PAN and pitch as a raw material and the manufacturing method.
  • carbon fibers having an average fiber diameter range of 5 ⁇ m to 10 ⁇ m for the PAN system, 5 ⁇ m to 20 ⁇ m for the pitch system, and several ⁇ m for the vapor phase growth can be used.
  • the average fiber length of the carbon fiber that can be used for the GDL according to the present embodiment is not particularly limited, but a generally used chopped fiber of 10 mm or less (more preferably 3 to 6 mm) can be made by paper. .
  • Carbon fiber has a low electric resistivity, when it is contained in the porous material layer, the electric charge generated in the catalyst layer can be collected more efficiently.
  • Carbon fiber has been industrially used as a reinforcing material for various composite materials in a wide range of fields such as aerospace due to its excellent specific strength and specific elastic modulus.
  • PAN-based carbon fibers or pitch-based carbon fibers that are widely used in industry are preferable.
  • the porous material layer is particularly preferably a PAN-based or pitch-based carbon fiber that does not contain graphitized (decarbonized) fiber.
  • “not containing graphitized (decarbonized) fibers” means that elements other than carbon (N, O, etc.) are included in the middle of the carbon atom chain forming the fibers.
  • the reason why such a fiber is particularly preferable will be described.
  • PAN-based carbon fiber is excellent in strength and elongation, but has a problem of low conductivity because it is non-graphitizable.
  • firing at a high temperature of about 2200 to 3000 ° C. is indispensable in order to improve conductivity, but there is a problem that the strength decreases at the same time.
  • pitch-based carbon fibers can be broadly classified into those derived from isotropic pitches and those derived from anisotropic pitches, but anisotropic pitches are generally used in order to achieve high performance.
  • the carbon fiber derived from anisotropic pitch is excellent in elasticity and strength due to the graphitizable nature of the raw material (anisotropic pitch), but has a problem of low elongation. Therefore, industrially, there is a possibility that the productivity of carbon fiber and the handling property at the time of compounding are inferior.
  • the above-described problem does not occur by configuring the porous material layer with fibers that are PAN-based or pitch-based carbon fibers and do not include graphitized fibers. And about the electroconductive fall of the porous material layer which consists of carbon fiber which does not contain a graphitized fiber, it can cover by presence of the electroconductive carbon layer mentioned later. In this way, the fuel cell gas diffusion layer according to the present embodiment can achieve both high conductivity and low cost.
  • the “graphitized fiber” in the present specification means a fiber obtained by firing at a temperature of 2000 ° C. or higher in an inert gas atmosphere for the purpose of improving the conductivity of the carbon fiber.
  • FIG. 36 is a schematic view showing a change in fiber in each step of manufacturing the PAN-based carbon fiber.
  • the PAN-based carbon fiber In order to impart high conductivity to the PAN-based carbon fiber, it is finally crystallized by performing a graphitization treatment.
  • the graphitization treatment that has been conventionally performed realizes a significant improvement in the conductivity of the porous material layer, while the cost of the porous material itself greatly increases. . That is, most of the cost is spent on the graphitization treatment in the production of the PAN-based carbon fiber.
  • the gas diffusion layer according to the present embodiment includes PAN-based carbon fibers, no graphitization treatment is performed in the manufacture of the PAN-based carbon fibers.
  • the changed fiber can be referred to as carbonized fiber instead of graphitized fiber.
  • the carbonized fiber has nitrogen atoms in the middle of the “carbon-carbon” bond, the conductivity of the PAN-based carbon fiber is much lower than that of the graphitized fiber.
  • the result is high conductivity without performing graphitization. Sex can be obtained. Thereby, both high conductivity and a significant cost reduction can be realized. Furthermore, the porosity in the porous material layer may be excessively increased by the graphitization treatment that has been conventionally performed.
  • a conductive carbon layer or conductive carbon particles it is possible to omit the graphitization treatment, and it is possible to prevent an excessive increase in porosity.
  • Organic fiber means conductive resin fiber.
  • the conductive resin fiber is a fiber that contains many carbon atoms and is easily carbonized by firing to form a carbon fiber, and as a result, exhibits conductivity.
  • Examples of the organic fiber include, but are not limited to, phenolic resin fiber, polyacrylonitrile fiber, polyethylene terephthalate fiber, and polybutylene terephthalate fiber.
  • a porous material layer contains a phenol-type resin fiber from a viewpoint that electrical conductivity can be ensured more reliably.
  • the fiber diameter range of the organic fiber is preferably 5 ⁇ m to 50 ⁇ m, more preferably 10 ⁇ m to 30 ⁇ m.
  • the fiber length of the organic fiber is not particularly limited because it is not chopped in the state of the organic fiber.
  • the porous material layer 352 preferably includes stainless steel, aluminum, or aluminum alloy fibers.
  • the porous material layer 352 contains stainless steel fibers in order to have not only mechanical strength, versatility, cost, ease of processing and high conductivity, but also sufficient resistance to an acidic atmosphere in the fuel cell. Is more preferable.
  • the electroconductivity of a contact surface with the porous material layer which comprises a separator is fully ensured. As a result, the durability of the separator is maintained by the corrosion resistance of the oxide film formed on the porous material layer itself made of stainless steel even if moisture enters the gaps in the rib shoulder film.
  • the fiber diameter range of the metal fiber is preferably 1 ⁇ m to 100 ⁇ m, more preferably 5 ⁇ m to 50 ⁇ m, and still more preferably 5 ⁇ m to 20 ⁇ m.
  • the fiber length of the metal fiber that can be used for the GDL according to the present embodiment can be made by making a paper of a chopped fiber of 10 mm or less that is generally used. The chopped fiber is more preferably 5 mm to 10 mm.
  • stainless steel examples include austenite, martensite, ferrite, austenite / ferrite, precipitation hardening, and the like detailed in the first embodiment.
  • aluminum alloy examples include the pure aluminum series, the aluminum / manganese series, and the aluminum / magnesium series described in detail in the first embodiment.
  • the tempering of the alloy is appropriately selected in addition to the above alloy types.
  • the purity of the titanium or aluminum is preferably 95% by mass or more, more preferably 97% by mass or more, and still more preferably 99%. It is at least mass%.
  • the porous material layer may include two or more selected from the group consisting of carbon fibers, metal fibers, and organic fibers.
  • the case where the fiber which comprises the said porous material layer consists of a carbon fiber and a metal fiber is demonstrated to an example.
  • the relationship between the carbon fiber and the metal fiber may be a form in which the carbon fiber and the metal fiber are simply mixed, or may be a form in which the metal fiber is present on the outer periphery so as to cover one carbon fiber.
  • the porous material layer may include non-conductive fibers and other components.
  • the content of the component having no conductivity is 50. It is preferable that it is below mass%. Moreover, it is more preferable that it is 10 mass% or less, and it is especially preferable that a porous material layer does not contain the component which does not have electroconductivity substantially.
  • the conductive carbon layer 354 is a layer containing conductive carbon. And as above-mentioned, the electroconductive fall as a price which aims at low cost in a porous material layer can be covered by presence of an electroconductive carbon layer. This is particularly the case for carbon fibers (in particular, PAN-based or pitch-based carbon fibers). Further, when metal fibers are used as the porous material layer, the presence of the conductive carbon layer ensures corrosion resistance as compared with the case of only the porous material layer 352 while ensuring the conductivity as the gas diffusion layer. Improved.
  • the intensity ratio of the measured from the Raman scattering spectroscopy D- band peak intensity I D and G- band peak intensity I G R is 1.3 or more.
  • the average peak measured by rotational anisotropy measurement by Raman scattering spectroscopy of the conductive carbon layer shows a two-fold symmetrical pattern.
  • most of the conductive carbon layer or the conductive carbon particles having an intensity ratio R (I D / I G ) of 1.3 or more is provided on or in the surface of the porous material layer.
  • crystalline graphite Present as crystalline graphite.
  • the “polycrystalline graphite” has an anisotropic graphite crystal structure (graphite cluster) in which graphene surfaces (hexagonal network surfaces) are laminated. Therefore, most of the conductive carbon layer or the conductive carbon particles constitute a laminate having a graphene surface because the strength ratio R (I D / I G ) is 1.3 or more.
  • the intensity ratio R (I D / I G ) between the D band peak intensity (I D ) and the G band peak intensity (I G ) is the graphite cluster size of the carbon material. It is used as an indicator such as the degree of disorder of the graphite structure (crystal structure defect) and the sp 2 bond ratio. That is, in this embodiment, it can be used as an index of contact resistance of the conductive carbon layer 354, and can be used as a film quality parameter for controlling the conductivity of the conductive carbon layer 354. Note that the R (I D / I G ) value is calculated by measuring the Raman spectrum of the carbon material, as in the first embodiment.
  • the R value is 1.3 or more.
  • the R value is preferably 1.4 to 2.0, more preferably 1.4 to 1.9, and further preferably 1.5 to 1.8.
  • a conductive carbon layer in which the conductivity in the stacking direction is sufficiently secured can be obtained.
  • R value is 2.0 or less, the reduction
  • an increase in internal stress of the conductive carbon layer itself can be suppressed, and adhesion with the porous material layer or the intermediate layer which is the base can be further improved.
  • the mechanism by which the above-mentioned effect is acquired by making R value 1.3 or more like this embodiment is estimated as demonstrated in 1st embodiment. That is, by controlling the R value to the above value, the amount and size of the graphite clusters are appropriately secured, and a conductive path from one surface of the conductive carbon layer 354 to the other surface is ensured. As a result, it is considered that the conductive carbon layer 354 is separately provided in addition to the porous material layer 352, so that a decrease in conductivity is prevented.
  • the size of the graphite cluster constituting the polycrystalline graphite is not particularly limited.
  • the average diameter of the graphite cluster is preferably about 1 nm to 50 nm, more preferably 2 nm to 10 nm.
  • the “diameter” of the graphite cluster can be measured in the same manner as in the first embodiment.
  • the conductive carbon layer 354 may be composed only of polycrystalline graphite, but the conductive carbon layer 354 can also include materials other than polycrystalline graphite.
  • Examples of carbon materials other than polycrystalline graphite include graphite particles such as carbon black, and fullerenes, carbon nanotubes, carbon nanofibers, carbon nanohorns, and carbon fibrils.
  • Specific examples of carbon black include, but are not limited to, ketjen black, acetylene black, channel black, lamp black, oil furnace black, and thermal black. Carbon black may be subjected to a graphitization treatment.
  • a material other than carbon contained in the conductive carbon layer 354 gold (Au), silver (Ag), platinum (Pt), ruthenium (Ru), palladium (Pd), rhodium (Rh), indium (In) And noble metals.
  • water-repellent substances such as polytetrafluoroethylene (PTFE), conductive oxides, and the like can also be given.
  • materials other than polycrystalline graphite only 1 type may be used and 2 or more types may be used together.
  • the thickness of the conductive carbon layer 354 is not particularly limited. However, it is preferably 1 nm to 1000 nm, more preferably 2 nm to 500 nm, and further preferably 5 nm to 200 nm. If the thickness of the conductive carbon layer is within such a range, sufficient conductivity can be ensured between the porous material layer constituting the gas diffusion layer and the separator. Moreover, a high corrosion resistance function can be given to the porous material layer.
  • the average peak measured by the rotational anisotropy measurement of the Raman scattering spectroscopic analysis for the Raman scattering spectroscopic analysis of the conductive carbon layer 354 is twice. Preferably it exhibits a symmetrical pattern.
  • the average peak measured by the rotational anisotropy measurement shows a two-fold symmetry pattern. This means that the surface direction of the graphene surface constituting the conductive carbon layer 354 is substantially coincident with the stacking direction of the conductive carbon layer 354. Means that Therefore, the conductivity in the conductive carbon layer 354 is ensured by the shortest path.
  • the Vickers hardness of the conductive carbon layer 354 is preferably 1500 Hv or less, more preferably 1200 Hv or less, and further preferably 1000 Hv or less. Especially preferably, it is 800 Hv or less.
  • the Vickers hardness is a value within such a range, excessive mixing of sp 3 carbon having no conductivity is suppressed, and a decrease in conductivity of the conductive carbon layer 354 is prevented.
  • the lower limit value of the Vickers hardness is not particularly limited, but if the Vickers hardness is 50 Hv or higher, the hardness of the conductive carbon layer 354 is sufficiently ensured.
  • the Vickers hardness of the conductive carbon layer 354 is more preferably 80 Hv or more, further preferably 100 Hv or more, and particularly preferably 200 Hv or more.
  • the content of hydrogen atoms in the conductive carbon layer 354 is preferably 30 atomic% or less with respect to all atoms constituting the conductive carbon layer 354. More preferably, it is 20 atomic% or less, More preferably, it is 10 atomic% or less.
  • the entire surface of the porous material layer 352 is preferably covered with the conductive carbon layer 354 directly or indirectly via the intermediate layer 356.
  • the ratio (coverage) of the area where the porous material layer 352 is covered with the conductive carbon layer 354 is preferably 100%. However, it is not limited to such a form, and the coverage may be less than 100%.
  • the coverage is preferably 50% or more. That is, it is preferable to cover 50% or more of the surface of the porous material layer 352 containing metal fibers with “conductive carbon”. Further, it is more preferably 80% or more, further preferably 90% or more, and most preferably 100%.
  • the coverage of the porous material layer 352 by the conductive carbon layer 354 is preferably 85% or more. is there. Further, it is more preferably 90% or more, and most preferably 92%.
  • the intermediate layer 356 described later is interposed between the porous material layer 352 and the conductive carbon layer 354 as in the present embodiment, the above coverage is obtained when the gas diffusion layer 4 is viewed from the stacking direction. Furthermore, the ratio of the area of the porous material layer 352 overlapping the conductive carbon layer 354 is meant.
  • the conductive carbon layer 354 in the present embodiment is present on the surface of the porous material layer 352, and between the conductive carbon layer 354 and the porous material layer 352.
  • an intermediate layer 356 made of metal may be further included.
  • the metal may be present in at least one of the porous material layer 352 and the conductive carbon layer 354 (not shown).
  • the GDL of this embodiment may include an intermediate layer 356 as a conductor.
  • the intermediate layer 356 has a function of improving adhesion between the porous material layer 352 and the conductive carbon layer 354 and a function of preventing elution of ions from the porous material layer 352.
  • the R value exceeds the upper limit value of the preferable range described above, the effect of providing the intermediate layer 356 is remarkably exhibited.
  • the intermediate layer may be provided even when the R value is included in the above-described preferable range.
  • the function and effect of the intermediate layer 356 can be significantly exhibited even when the porous material layer 352 is made of aluminum or an alloy thereof.
  • the intermediate layer is an arbitrary layer, and the intermediate layer does not necessarily exist.
  • a preferable form in the case of including an intermediate layer will be briefly described.
  • the material constituting the intermediate layer 356 is not particularly limited as long as it provides adhesion, but the same material as that of the intermediate layer 32 of the first embodiment can be used. In particular, when the above-described metal with little ion elution or a carbide or nitride thereof is used, the corrosion resistance of the porous material layer can be significantly improved. Further, the structure of the intermediate layer 356 is not particularly limited, but can be a columnar structure similar to the intermediate layer 32 of the first embodiment.
  • the thickness of the intermediate layer 356 is preferably 0.005 ⁇ m to 10 ⁇ m, more preferably 0.005 ⁇ m to 0.1 ⁇ m, and still more preferably 0.005 ⁇ m to 0.01 ⁇ m.
  • the intermediate layer itself is effective in terms of suppressing peeling due to thermal expansion between the conductive carbon layer and the fiber, and preventing corrosion when the metal constituting the fiber has low corrosion resistance.
  • the thickness is 10 ⁇ m or more, there is a high possibility that the pores of the porous layer are clogged depending on the thickness of the intermediate layer.
  • the thickness of the intermediate layer can be measured by AES depth analysis.
  • the surface of the intermediate layer 356 on the conductive carbon layer 354 side is preferably rough at the nano level. According to such a configuration, the adhesion of the conductive carbon layer 354 formed on the intermediate layer 356 to the intermediate layer 356 is further improved.
  • the thermal expansion coefficient of the intermediate layer 356 is a value close to the thermal expansion coefficient of the metal constituting the porous material layer 352
  • the adhesion between the intermediate layer 356 and the porous material layer 352 is improved.
  • the adhesion between the intermediate layer 356 and the conductive carbon layer 354 may decrease.
  • the thermal expansion coefficient of the intermediate layer 356 is close to the thermal expansion coefficient of the conductive carbon layer 354, the adhesion between the intermediate layer 356 and the porous material layer 352 may be reduced.
  • the thermal expansion coefficient ( ⁇ mid ) of the intermediate layer, the thermal expansion coefficient ( ⁇ sub ) of the porous material layer, and the thermal expansion coefficient ( ⁇ c ) of the conductive carbon layer satisfy the following relationship: It is preferable to do.
  • ⁇ sub and ⁇ mid are the same value corresponds to the case where the constituent metal of the metal fiber of the porous material layer and the constituent metal of the intermediate layer are the same.
  • the intermediate layer 356 may be present on at least one surface of the porous material layer 352. Moreover, when a conductive carbon layer exists in both surfaces of a porous material layer, it is preferable to interpose an intermediate
  • the conductive carbon layer 354 may exist on the surface of the porous material layer 352.
  • the conductive carbon layer 354 further includes a hydrophilic layer 358 composed of one or more selected from the group consisting of metals, metal nitrides, metal carbides, and metal oxides. May be.
  • the hydrophilization layer 358 is arrange
  • hydrophilic layer The function of such a hydrophilic layer will be described below. Although water is generated by the power generation of the battery, it is highly desirable that this water be quickly transported to the separator and discharged. At that time, if the hydrophilic layer is disposed on the surface of the gas diffusion layer (4a, 4b) where the separator (5a, 5b) is present, the hydrophilicity at the separator interface is improved, and the catalyst layer Rapid discharge of water from (3a, 3b) to the separator side can be promoted.
  • a groove-like flow path constituted by a plurality of recesses present in the separators (5a, 5b) is involved in drainage. Therefore, in the hydrophilic layer of the gas diffusion layer (4a, 4b) on the separator (5a, 5b) side, the portion of the hydrophilic layer in contact with the recess is made of metal so as to have a high degree of hydrophilicity. It is preferred that On the other hand, the portion of the hydrophilic layer in contact with the convex portion may be composed of one or more selected from the group consisting of metals, metal nitrides, metal carbides, and metal oxides because hydrophilicity is not important. .
  • hydrophilized layer may not be present in a portion of the hydrophilized layer in contact with the convex portion.
  • the hydrophilization layer may take the form of a partial (discontinuous) “layer” that exists on the surface of the gas diffusion layer.
  • the metal constituting the hydrophilic layer may contain one or more selected from the group consisting of noble metals, metal elements constituting the separator, and metal elements included in the surface treatment of the separator.
  • the noble metal a noble metal that can be included in the conductive carbon layer 354 can be given.
  • a metallic element which comprises a separator iron, titanium, aluminum, copper, and these alloys are mentioned, for example. Examples of these alloys include alloys such as stainless steel constituting the metal fibers.
  • Examples of the metal element contained in the surface treatment of the separator include the elements used in the first to third embodiments. When the metal is a noble metal, not only can hydrophilicity be improved, but contact resistance can be significantly reduced.
  • the metal nitride, metal carbide, and metal oxide can include all of the above-described metal nitride, carbide, and oxide.
  • FIG. 34 shows the hydrophilic layer 358.
  • the hydrophilized layer 358 is shown as a continuous layer.
  • a discontinuous layer form that is, a metal dispersed layer form as described above may be employed.
  • a porous material layer 352, a conductive carbon layer 354, an optional intermediate layer 356, and a hydrophilic layer 358 are present as conductors.
  • neither the intermediate layer 356 nor the hydrophilic layer 358 may be present, and at least one of them may be present.
  • the cross-sectional view of the gas diffusion layer in FIG. 34 shows a structure in which an intermediate layer and a conductive carbon layer are laminated on the porous material layer.
  • the cross-sectional view of the present embodiment is not limited to this, and may have a structure in which an intermediate layer and a conductive carbon layer are “laminated” inside a porous material layer composed of fibers.
  • the hydrophilic layer since the function of the hydrophilic layer is to promote discharge of water to the separator side, the hydrophilic layer does not matter where the conductive carbon layer and the intermediate layer are provided in the porous material layer. It is preferably present on the porous material layer.
  • the gas diffusion layer of the present embodiment preferably has an electric resistance value in the thickness direction of 1 m ⁇ ⁇ cm 2 or less.
  • the electric resistance value in the thickness direction of the gas diffusion layer is 2.0 m ⁇ or less, the battery performance is easily improved, and embrittlement of the components of the gas diffusion layer due to heat generation can be effectively prevented.
  • the electric resistance value in the thickness direction is an electric resistance value measured between two test electrodes with a gas diffusion layer sandwiched between two gold-plated 50 mm square test electrodes (thickness 10 mm) at a pressure of 1 MPa. (M ⁇ ).
  • the thickness of the gas diffusion layer of this embodiment can be set to 100 ⁇ m to 300 ⁇ m, but the thickness can be appropriately adjusted in view of the shape and performance of the cell. Moreover, in the said gas diffusion layer, since a fiber component has electroconductivity, since fiber mutually fuse
  • the method for producing a fuel cell gas diffusion layer according to the present embodiment includes a step of forming a conductive carbon layer or conductive carbon particles on or in the surface of the porous material layer.
  • a commercial item can be used.
  • some of the porous material layers in the present embodiment are not currently distributed as commercial products, such as PAN-based or pitch-based carbon fibers that are not graphitized. Therefore, the manufacturing method and conditions of the special PAN-based or pitch-based carbon fiber will be described later.
  • a layer containing conductive carbon is stacked on the porous material layer at the atomic level using conductive carbon (for example, graphite) as a target. .
  • conductive carbon for example, graphite
  • a conductive carbon layer can be formed. In this way, the adhesion between the directly adhered conductive carbon layer and the porous material layer and the vicinity thereof is maintained for a long period of time due to intermolecular forces and the entry of a few carbon atoms.
  • a PVD method such as a sputtering method or an ion plating method, an ion beam evaporation method such as an FCVA method, or the like
  • a sputtering method include a magnetron sputtering method, a UBMS method, a dual magnetron sputtering method, and an ECR sputtering method.
  • the ion plating method include an arc ion plating method.
  • it is preferable to use sputtering method and an ion plating method and it is especially preferable to use sputtering method.
  • a carbon layer having a low hydrogen content can be formed.
  • the ratio of bonds between carbon atoms (sp 2 hybrid carbon) can be increased, and excellent conductivity is achieved.
  • the film can be formed at a relatively low temperature, and damage to the porous material layer can be minimized.
  • the film quality of the deposited layer can be controlled by controlling the bias voltage and the like.
  • a conductive carbon layer can be manufactured continuously and efficiently by forming a conductive carbon layer by sputtering method.
  • the porous material layer contains metal fibers
  • FIG. 37 is a schematic view showing a film forming apparatus for an intermediate layer and a conductive carbon layer using a sputtering method.
  • the conductive carbon layer is formed by sputtering, it is preferable to exhaust the gas through the gas exhaust port 366 so that the degree of vacuum in the chamber 364 is about 3 to 10 Pa.
  • Ar is introduced preferably through the atmospheric gas inlet 368 at about 0.1 to 1 Pa.
  • the temperature of the gas diffusion layer itself is not particularly limited as long as it is in the range of room temperature (25 ° C.) to 200 ° C., but preferably the temperature is set according to the material of GDL (particularly the porous material layer).
  • Sputtering is performed by ejecting a target material (such as Cr or graphite) from the target 370 to the porous material layer 372.
  • a negative bias voltage may be applied to the porous material layer during sputtering.
  • the conductive carbon layer having a structure in which graphite clusters are densely assembled is formed by the ion irradiation effect. Since such a conductive carbon layer exhibits excellent conductivity, a gas diffusion layer having a low contact resistance with other members (for example, a catalyst layer or a separator) is provided.
  • the magnitude (absolute value) of the negative bias voltage to be applied is not particularly limited, and a voltage capable of forming a conductive carbon layer is employed. As an example, the magnitude of the applied voltage is preferably 50 to 500V, more preferably 100 to 300V.
  • the conductive carbon layer 354 is formed by the UBMS method, it is preferable to form an intermediate layer in advance and form the conductive carbon layer thereon. Thereby, the electroconductive carbon layer excellent in adhesiveness with a base layer is formed.
  • the conductive carbon layer is formed by another method, a conductive carbon layer having excellent adhesion to the porous material layer is formed even when the intermediate layer is not present.
  • a gas diffusion layer in which the conductive carbon layer 354 is formed on one surface of the porous material layer 352 is manufactured.
  • the other surface of the porous material layer 352 is made conductive by the same method as described above.
  • a carbon layer may be formed.
  • the intermediate layer is formed on at least one surface of the porous material layer before the conductive carbon layer forming step described above.
  • the process to do is performed.
  • the same method as described above for the formation of the conductive carbon layer is employed. However, it is necessary to change the target to the constituent material of the intermediate layer.
  • a conductive carbon layer may be formed on the intermediate layer formed by the above process.
  • the method for forming the conductive carbon layer on the surface of the intermediate layer the same method as described above for the formation of the conductive carbon layer on the surface of the porous material layer is employed.
  • a step (2) of forming a hydrophilic layer may be performed.
  • a sputtering method that targets at least one selected from the group consisting of metals, metal nitrides, metal carbides, and metal oxides, and metal plating can be used.
  • the steps (1) to (2) can be performed easily and continuously by sputtering a predetermined metal or the like.
  • the step (2) is carried out by plating, if the porous material layer is a continuous sheet, it can be processed in a roll-to-roll method in a solution, and therefore can be manufactured efficiently and at low cost.
  • a desired gas diffusion layer can be formed by performing step (2) after step (1).
  • a hydrophilic layer can be formed on the separator-side surface of the gas diffusion layer, and further, there is an advantage that the manufacturing time is greatly shortened.
  • the hydrophilization material which comprises a hydrophilization layer exists in not only the separator side surface of a gas diffusion layer but the whole gas diffusion layer.
  • the hydrophilic layer may take a discontinuous layer form, that is, a layer form in which a metal is dispersed. Therefore, it can be said that it is sufficiently meaningful to perform the steps (1) and (2) at the same time (almost at the same time) in view of the advantages of cost and labor reduction due to the significant shortening of the manufacturing time.
  • the metal used in the plating process is preferably a noble metal or a metal element constituting a separator.
  • the metal is a noble metal, not only can hydrophilicity be improved, but contact resistance can be significantly reduced. Further, when the metal is a metal element constituting the separator, it is possible to effectively prevent the corrosion that occurs when different metals come into contact with each other.
  • step (1) and step (2) can be rephrased as follows.
  • a conductive carbon layer or conductive carbon particles and / or a hydrophilic layer can be formed by sputtering.
  • a plating process can be used instead of the sputtering method.
  • FIG. 38 is a diagram showing a general PAN-based carbon fiber manufacturing process and a PAN-based carbon fiber manufacturing process in the present embodiment.
  • this embodiment has the greatest feature in that no graphitization is performed.
  • a finishing (filament cutting) treatment including surface treatment and sizing is performed without performing graphitization treatment.
  • the surface of the fiber is preferably subjected to a water-repellent treatment using a conventionally known fluorine-based liquid. And it can calcinate at the end and can obtain the roll-shaped sheet of a gas diffusion layer.
  • a conventionally known one as shown in FIG. 38 may be applied.
  • the manufacturing method of the PAN-based carbon fiber in the present invention is not limited to the following, and the method and conditions are appropriately changed. Etc. may be performed.
  • a monomer mainly composed of acrylonitrile is polymerized to obtain a PAN-based polymer.
  • the PAN-based polymer is spun by wet and / or dry processes to produce PAN-based precursor fibers.
  • the PAN polymer preferably contains 90% by weight or more, more preferably 95% by weight or more of acrylonitrile, which is the main component of the monomers. If necessary, other monomers copolymerizable with acrylonitrile may be added for copolymerization. In spinning, the polymer and copolymer are dissolved in a solvent or an aqueous solution to obtain a spinning dope.
  • the other monomer is not particularly limited as long as it is copolymerizable with acrylonitrile, and examples thereof include butadiene and styrene.
  • examples of the solvent for the spinning dope include organic solvents such as dimethyl sulfoxide, dimethylformamide, dimethylacetamide and N-methylpyrrolidone.
  • examples of the aqueous solution of the spinning dope include a zinc chloride aqueous solution and a sodium thiocyanate aqueous solution.
  • Such spinning dope is generally spun into fibers by wet and / or dry methods. If necessary, the film is stretched in a heating medium such as pressurized steam to adjust the orientation, or in some cases, further subjected to heat treatment at 130 to 200 ° C. and wound to obtain a PAN-based precursor fiber.
  • a heating medium such as pressurized steam to adjust the orientation, or in some cases, further subjected to heat treatment at 130 to 200 ° C. and wound to obtain a PAN-based precursor fiber.
  • the basic skeleton of the PAN-based precursor fiber is shown in FIG.
  • the PAN-based carbon fiber in the present embodiment is manufactured from the PAN-based precursor fiber.
  • the PAN precursor fiber is subjected to stabilization treatment.
  • the film is stretched 0.95 to 1.05 times while being heated at 200 to 350 ° C., more preferably 200 to 300 ° C., and further preferably 230 to 270 ° C. in an oxidizing atmosphere such as air.
  • the PAN-based precursor fiber is converted into a flame-resistant fiber.
  • the treatment time is 80 to 160 minutes, and the degree of pressurization is, for example, more than 1.3 g / cm 3 .
  • the basic skeleton of the flameproof fiber is shown in FIG.
  • the obtained flame-resistant fibers are activated while being heated in an oxidizing atmosphere such as air, preferably at 800 to 1200 ° C., to obtain activated carbon fibers.
  • the activated carbon fiber (or flame resistant fiber) obtained is carbonized.
  • the film is stretched 1.0 to 1.1 times while heating at a maximum temperature of preferably 600 to 900 ° C, more preferably 700 to 800 ° C.
  • the carbonized fiber is stretched 0.95 to 1.0 times while heating at a maximum temperature of preferably 1000 to 1800 ° C., more preferably 1200 to 1500 ° C. in an inert atmosphere such as nitrogen. Is obtained.
  • the basic skeleton of the flameproof fiber is shown in FIG. As shown in FIG. 36 (c), the carbonized fiber has a nitrogen atom in the middle of the “carbon-carbon” bond, so its conductivity is higher than that of the graphitized fiber after graphitization. Low.
  • a graphitization treatment which is essential in a general method for producing a PAN-based carbon fiber will be described just in case. While the carbonized fiber is heated at a maximum temperature of 2000 to 3000 ° C., more preferably 2200 to 3000 ° C., and further preferably 2200 to 2800 ° C. in an inert atmosphere such as nitrogen, 1.01 to 1 2. Stretch 2 times. At this time, the processing time is, for example, 150 to 400 seconds.
  • the basic skeleton of the graphitized fiber is shown in FIG.
  • the graphitized fiber thus obtained is subjected to a surface oxidation treatment, preferably an electrolytic oxidation treatment of 10 to 200 coulomb / g in an acid or alkaline aqueous solution, to produce a functional group that enhances adhesion on the fiber surface.
  • a surface oxidation treatment preferably an electrolytic oxidation treatment of 10 to 200 coulomb / g in an acid or alkaline aqueous solution.
  • the finishing treatment (filament cutting) including surface treatment and sizing is performed as it is.
  • the chopped fiber obtained by this treatment is made into paper as in the case of making paper.
  • a conventionally known method may be applied to the papermaking method and conditions.
  • the material to be used include components of the porous material layer (such as carbon fiber), activated carbon, pulp (such as cellulose fiber), and artificial graphite fine powder.
  • the addition ratio of each material is not particularly limited as long as it can be made into paper. There are no particular restrictions on the size and weight of the paper to be obtained.
  • the conditions for the subsequent papermaking firing are not particularly limited as long as the conditions are set at an optimal temperature and time that can realize graphitization of the material contained in the papermaking. As an example, the temperature may be 1000 to 2500 ° C. for 1 to 48 hours.
  • the surface of the fiber is preferably subjected to a water-repellent treatment using a conventionally known fluorine-based liquid.
  • the paper-made sheet preferably has a thickness of 0.2 to 2 mm / sheet and a density of 100 to 250 g / m 2 . 1 to 5 sheets are laminated and fired in an inert gas atmosphere such as nitrogen or argon. Firing may be performed, for example, between graphite plates in order to prevent warpage of the sheet.
  • the firing temperature is preferably raised to about 800 ° C. or lower (maximum temperature reached) for 5 to 100 hours.
  • the final temperature for firing is not particularly limited. Thereby, the roll-shaped sheet of a gas diffusion layer can be obtained.
  • the water repellent is not particularly limited, but fluorine-based high repellents such as polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), polyhexafluoropropylene, and tetrafluoroethylene-hexafluoropropylene copolymer (FEP). Examples thereof include molecular materials, polypropylene, and polyethylene.
  • PTFE polytetrafluoroethylene
  • PVdF polyvinylidene fluoride
  • FEP tetrafluoroethylene-hexafluoropropylene copolymer
  • the gas diffusion layer may have a carbon particle layer (microporous layer) made of an aggregate of carbon particles containing a water repellent on the catalyst layer side of the substrate. good.
  • the carbon particles contained in the carbon particle layer are not particularly limited, and carbon black, graphite, expanded graphite and the like are appropriately employed. Of these, carbon blacks such as oil furnace black, channel black, lamp black, thermal black, and acetylene black are preferably used because of excellent electron conductivity and a large specific surface area.
  • the average particle diameter of the carbon particles is preferably about 10 nm to 100 nm. Thereby, while being able to obtain the high drainage property by capillary force, the contact property with a catalyst layer can also be improved.
  • water repellent used for the carbon particle layer examples include the same water repellents as described above. Of these, fluorine-based polymer materials are preferably used because of their excellent water repellency and corrosion resistance during electrode reaction.
  • the mixing ratio of the carbon particles to the water repellent in the carbon particle layer is about 90:10 to 40:60 (carbon particles: water repellent) in mass ratio in consideration of the balance between water repellency and electron conductivity. Is good.
  • the gas diffusion layer for fuel cells in this embodiment can be suitably used as various gas diffusion layers for fuel cells such as PAFC, MCFC, SOFC or AFC in addition to PEFC.
  • fuel cells such as PAFC, MCFC, SOFC or AFC in addition to PEFC.
  • the conductivity can be improved and the cost can be greatly reduced.
  • separators of the first to third embodiments are preferably used, but other known separators can also be used.
  • Example IV-1 carbonized GDL was prepared.
  • the carbonized GDL is a porous material layer made of PAN-based carbon fiber that has been subjected to carbonization treatment.
  • a bias voltage of 140 V was applied to the gas diffusion layer without considering the material of the porous material layer. 99% or more of Cr was used as a target. In this way, a Cr layer having a thickness of 20 nm was laminated as an intermediate layer on the surface of the porous material layer.
  • a conductive carbon layer was laminated by UBMS sputtering. Except for using 99% or more of graphite as a target, a conductive carbon layer was laminated by the same method and conditions as the lamination of the intermediate layer. The obtained conductive carbon layer was confirmed to have a laminated structure with a graphene surface, and its thickness was 7 ⁇ m.
  • Comparative Example IV-1 As a comparative example, commercially available graphitized GDL, TGP-H-90 (manufactured by Toray Industries, Inc.) was used.
  • Example IV-2 A GDL for a fuel cell was produced, in which a PAN-based carbon fiber that had been subjected to carbonization treatment consisted of only a porous material layer. Incidentally, the same porous material layer as in Example IV-1 was used. Note that the chromium (Cr) layer and the conductive carbon layer are not stacked. Therefore, the obtained GDL for a fuel cell does not have a graphene-surface stacked body structure.
  • the R value of the conductive carbon layer was measured. Specifically, first, the Raman spectrum of the conductive carbon layer was measured using a microscopic Raman spectrometer. Then, 1300 ⁇ 1400 cm peak intensity of the bands (D-band) located -1 (I D), the peak area ratio of the peak intensity (I G) of band (G-band) located 1500 ⁇ 1600 cm -1 ( I D / I G ) was calculated and used as the R value. The results obtained are shown in Table 5 below.
  • FIG. 39 is a diagram showing a method for measuring the contact resistance between the gas diffusion layer for a fuel cell and the separator obtained in the examples and the comparative examples.
  • the separator 360 a stainless steel plate having a gold-plated surface on the gas diffusion layer 362 side was used.
  • the produced gas diffusion layer 362 is sandwiched between a pair of separators 360, power is connected to both ends of the gas diffusion layer 362, and the measuring device is held while applying a 1 MPa load from the vertical direction to each main surface of the separator 360. Configured. A constant current of 1 A was passed through both ends of this measuring apparatus, and the contact resistance value of the laminate was calculated from the voltage value and Ohm's law at that time. The results obtained are shown in Table 5 below.
  • Example IV-1 As shown in Table 5, the contact resistance values of Example IV-1 and Comparative Example IV-1 are almost the same. Therefore, according to the present embodiment, it has been confirmed that the cost can be significantly reduced while ensuring the same conductivity as compared with the conventional gas diffusion layer for fuel cells.
  • FIG. 40 shows the relationship between the increase in the conductive carbon layer and the contact resistance.
  • the PAN-based carbonized fiber itself in this embodiment is inferior to the PAN-based carbon fiber subjected to the graphitization treatment in terms of conductivity.
  • the contact resistance decreases in proportion to the amount of the conductive carbon layer laminated.
  • the gas diffusion layer according to this embodiment is equivalent to a gas diffusion layer made of graphitized PAN-based carbon fiber from the viewpoint of conductivity.
  • the PAN-based carbonized fiber according to the present embodiment does not perform graphitization, and thus can greatly reduce the cost.
  • both the carbon fiber and the conductive carbon are detected as carbon (C) by Auger electron spectroscopy. Therefore, the two cannot be distinguished. Therefore, when the intermediate layer before forming the conductive carbon layer is formed, it is assumed that the conductive carbon layer is always formed on the constituent elements of the intermediate layer. AES surface mapping was performed on the constituent metals. Through such a process, the ratio of “conductive carbon” to the carbon fiber was calculated.
  • the chamber was evacuated to about 3 to 10 Pa with respect to the gas diffusion layer obtained in Example IV-1, and then about 1 Pa of argon gas was introduced.
  • the temperature of the gas diffusion layer itself was set to 80 ° C. without considering the material.
  • a bias voltage of 140 V was applied to the gas diffusion layer without considering the material of the porous material layer.
  • 99% or more of Au was used as a target.
  • an Au layer (hydrophilic layer) having a thickness of 5 nm was laminated on the surface of the conductive carbon layer.
  • the arrangement of Au was calculated by surface mapping and image analysis of Auger electron spectroscopy because the porous material layer is porous.
  • the static contact angle of water with respect to the area ratio (Au area / conductive carbon area) of conductive carbon and Au was measured.
  • the contact angle was measured according to JIS K6768. More specifically, the static contact angle was measured using pure water (6 ⁇ L) under the conditions of 24 ° C. and humidity (RH) 49%.
  • DM700 ⁇ / 2 method manufactured by Kyowa Interface Science Co., Ltd. was used. A graph of the measurement results is shown in FIG.
  • the vacuum degree of the chamber was evacuated to about 3 to 10 Pa with respect to the gas diffusion layer obtained in Example IV-1, and then about 5 Pa of argon gas was introduced.
  • the temperature of the gas diffusion layer itself was set to 80 ° C. without considering the material.
  • Example IV-1 a sufficiently small contact resistance can be secured by disposing a conductive carbon layer in the gas diffusion layer.
  • the contact resistance can be further reduced by further arranging Au.
  • the presence of the hydrophilic layer in the gas diffusion layer makes it possible to quickly discharge water from the catalyst layer to the separator side.
  • the hydrophilic layer is made of a metal oxide, such hydrophilicity can be obtained.
  • the hydrophilic layer is composed of a non-metal oxide (Au or the like), in addition to the hydrophilic property, the conductivity is extremely excellent, so that an effect of reducing contact resistance can be obtained.
  • the conductive member according to the present embodiment includes a fuel cell separator (conductive laminate) in which a metal substrate, an intermediate layer, and a conductive carbon layer are laminated, and a gas diffusion layer including a gas diffusion substrate having a plurality of pores. And.
  • the conductive carbon layer and the gas diffusion layer are stacked so as to face each other.
  • hydrophilic conductive particles are dispersed in a region on the surface of the conductive carbon layer and in contact with the gas diffusion layer. Further, the particle diameter of the conductive particles and the distance between the conductive particles are not more than the distance between the holes of the gas diffusion substrate.
  • the polymer electrolyte fuel cell (PEFC) according to this embodiment also has the same basic configuration as the PEFC according to the first embodiment. Specifically, as shown in FIG. 1, the PEFC has a solid polymer electrolyte membrane 2 and a pair of catalyst layers (an anode catalyst layer 3a and a cathode catalyst layer 3b) that sandwich the membrane. The laminate of the solid polymer electrolyte membrane 2 and the catalyst layers (3a, 3b) is further sandwiched between a pair of gas diffusion layers (anode gas diffusion layer 4a and cathode gas diffusion layer 4b). Thus, the solid polymer electrolyte membrane 2, the pair of catalyst layers (3a, 3b), and the pair of gas diffusion layers (4a, 4b) constitute the membrane electrode assembly 9 in a stacked state.
  • the MEA 9 is further sandwiched between a pair of separators (anode separator 5a and cathode separator 5b). That is, the separators (5a, 5b) are disposed adjacent to the gas diffusion layers (4a, 4b), and the adjacent separators (5a, 5b) and the gas diffusion layers (4a, 4b) include the conductive members (8a, 8b). Constitute.
  • FIG. 43 is a cross-sectional view showing a schematic configuration of the conductive member 408 according to the present embodiment.
  • the conductive member 408 includes a gas diffusion layer 404 and a separator 405.
  • the separator 405 includes a metal substrate 452 and a conductive carbon layer 454.
  • hydrophilic conductive particles 457 are dispersed in a region 409 that is in contact with the gas diffusion layer 404 on the surface of the conductive carbon layer 454.
  • an intermediate layer 456 is interposed between the metal substrate 452 and the conductive carbon layer 454.
  • the separator 405 is arranged so that the conductive carbon layer 454 is located on the MEA 9 side.
  • each component of the conductive member 408 of this embodiment will be described in detail.
  • the metal substrate 452 is a main layer of the separator 405, and contributes to ensuring conductivity and mechanical strength. And the metal which comprises the metal base material 452 can use the metal similar to the metal base material 31 in 1st embodiment.
  • the conductive carbon layer 454 is a layer containing conductive carbon. The presence of this layer improves the corrosion resistance as compared with the case of only the metal substrate 452 while ensuring the conductivity of the separator 405. As such a conductive carbon layer 454, the conductive carbon layer 33 of the first embodiment can be used.
  • the hydrophilic conductive particles 457 are conductive particles having hydrophilicity.
  • the hydrophilic conductive particles 457 are dispersed in a region 409 that is in contact with the gas diffusion layer 404 on the surface of the conductive carbon layer 454.
  • the conductive particles 457 hydrophilicity is imparted to the conductive carbon layer 454, conductivity is further improved, and contact resistance with the gas diffusion layer 404 can be reduced.
  • the conductive particles may be present on the surface of the conductive carbon layer other than the contact region 409 or inside the conductive carbon layer.
  • the conductive particles 457 be present on the surface layer of the conductive carbon layer 454 in order to exert a contact resistance reduction effect and a hydrophilicity improvement effect and reduce the manufacturing cost. More specifically, it is preferable that uniform dispersion is performed in a plane with a minimum thickness. For this reason, the thickness and dispersibility largely depend on the manufacturing method and conditions.
  • the average thickness of the conductive carbon layer confirmed in this embodiment is preferably 0.005 ⁇ m to 1 ⁇ m.
  • the conductive particle is not particularly limited as long as it is a material having conductivity and hydrophilicity.
  • the hydrophilic property means smaller than the static contact angle.
  • the hydrophilicity preferably means that the static contact angle with water is 70 ° or less, more preferably 60 ° or less.
  • the conductive particles preferably include at least one selected from the group consisting of noble metals, alloys containing noble metals, conductive nitrides, and conductive oxides.
  • the noble metal is selected from the group consisting of gold (Au), silver (Ag), platinum (Pt), palladium (Pd), rhodium (Rh), iridium (Ir), ruthenium (Ru), and osmium (Os). At least one is preferred.
  • the alloy containing a noble metal include a gold-cobalt alloy (Au—Co), a gold-nickel alloy (Au—Ni), a palladium-nickel alloy (Pd—Ni), and the like.
  • the conductive nitride include CrN, TiN, ZrN, and HfN.
  • MBa 2 Cu 3 O 7-x (M is Y or a rare earth element other than Ce, Pr, and Tb), SnO 2 , In 2 O 3 , CrO 2 , Fe 3 O 4 , IrO 2 , OsO 2 , PtO 2 , ReO 2 ( ⁇ ), ReO 3 , RhO 2 , RuO 2 , WO 2 , W 18 O 49 , V 2 O 3 , V 7 O 13 , V 8 O 15 , V 6 O 13
  • platinum (Pt), gold (Au), and silver (Ag) are preferable from the viewpoint of high conductivity, and silver (Ag) is more preferable from the viewpoint of cost.
  • Gold (Au) is also preferably used in terms of cost in consideration of utilization including recycling.
  • the alloy containing a noble metal, a conductive nitride, and a conductive oxide you may use individually by 1 type, and may mix and use 2 or more types.
  • the particle diameter of the conductive particles and the distance between the conductive particles are preferably not more than the distance between the holes of the gas diffusion substrate. In such a case, a contact point between the conductive particles and the gas diffusion base can be secured, and the contact resistance with the gas diffusion layer is reduced.
  • “distance between conductive particles” means the distance between the centers of the two closest conductive particles.
  • the “inter-hole distance” means the distance between the centers of the two closest holes.
  • the “distance between the conductive particles” is calculated as an average value of the distance between the conductive particles observed in several to several tens of fields using an observation means such as a scanning electron microscope or a transmission electron microscope. Shall be adopted.
  • the “inter-hole distance” is the average of inter-hole distances observed in several to several tens of fields in the cross section of the gas diffusion substrate using an observation means such as a scanning electron microscope or a transmission electron microscope. Calculated as a value.
  • the distance between the holes corresponds to the fiber diameter.
  • the gas diffusion base is composed of fibers (fiber assembly)
  • the distance between the holes corresponds to the fiber diameter.
  • the gas diffusion base is composed of carbon fibers 458, the particle diameter of the conductive particles 457 and the distance between the conductive particles 457 are not more than the diameter of the carbon fibers 458. It is preferable.
  • the gas diffusion substrate is composed of particles (particle aggregate)
  • the distance between the holes corresponds to the diameter of the particles.
  • the gas diffusion base is composed of carbon particles 458, the particle diameter of the conductive particles 457 and the distance between the conductive particles 457 are not more than the diameter of the carbon particles 458. It is preferable.
  • the gas diffusion base is composed of fibers or particles, a contact point between the conductive particles and the carbon fibers or the carbon particles can be reliably ensured.
  • the gas diffusion substrate is made of a porous metal such as a wire mesh or a punched press plate having a through hole
  • this corresponds to the shortest distance between the hole centers.
  • the gas diffusion substrate is composed of a porous metal 460 having a through-hole 461
  • the particle diameter of the conductive particles 457 and the distance between the conductive particles 457 are determined as the porous material 457.
  • the distance between the holes of the metal 460 is preferably equal to or less than the distance. In such a case, since the fine particles exist at intervals smaller than the width of the base metal within the distance between the holes in the porous metal, a large number of contacts can be secured.
  • the particle diameter of the conductive particles and the distance between the conductive particles are 1 nm to 7 ⁇ m.
  • the coverage of the contact area with conductive particles is preferably 1% or more. If it is 1% or more, the hydrophilicity and electroconductivity improvement effect by electroconductive particle will be acquired. More preferably, it is 2 to 100%, still more preferably 3 to 100%, and particularly preferably 10 to 100%. If it is more than this lower limit, hydrophilicity and electroconductivity will improve notably.
  • the upper limit is preferably as large as possible from the viewpoint of improving hydrophilicity and conductivity, and is preferably 100% (complete coverage). However, in consideration of cost, as long as hydrophilicity and conductivity are ensured. A smaller coverage is preferred.
  • the contact resistance between the two elements is calculated from the sum of the volume resistivity ( ⁇ 1 , ⁇ 2 ) of the two members constituting the contact and the reciprocal of the contact radius (1 / a n ).
  • ⁇ 1 and ⁇ 2 are values specific to the material.
  • ⁇ 1 and ⁇ 2 are gold (Au) and This is the volume resistivity of the carbon fiber. Therefore, it can be seen that the contact resistance depends on the number of contacts and the radius of the contacts.
  • the present inventors have found that when the coverage of the conductive particles is not less than the above lower limit, the contact with the gas diffusion substrate can be significantly increased and the contact resistance can be reduced. .
  • the coverage by the conductive particles is the above lower limit value. If it was above, it was recognized that contact resistance is reduced.
  • the contact point between the gas diffusion substrate and the conductive particles depends on the material and size of the conductive particles and the gas diffusion substrate, and the surface roughness and material of the contact region of the conductive carbon layer.
  • the contact point between the conductive particles dispersed in the contact region and the gas diffusion base can be increased, so that the contact resistance can be reduced.
  • the hydrophilic surface has a higher hydrophilicity as the surface roughness is larger.
  • the larger the surface roughness the more the hydrophilic effect. Demonstrate. For this reason, it is preferable to appropriately adjust the coverage of the conductive particles in accordance with the conductive particles, gas diffusion base, and conductive carbon layer (contact region) to be used.
  • the contact angle of water in the contact region in which the conductive particles are dispersed is preferably 70 ° or less, more preferably 0 to 60 °, and further preferably 45 to 50 °.
  • the drainage performance of the separator surface that becomes the water flow path is further improved. Therefore, even if it is a narrow flow path in a separator with a small rib pitch (having a fine uneven shape) in which water discharge is a problem, water can be efficiently drained.
  • the contact angle is measured based on the wettability test method described in JIS K6768.
  • the electroconductive particle should just exist on the surface of the electroconductive carbon layer formed in at least one side of the metal base material.
  • conductive particles may be dispersed on the surfaces of both conductive carbon layers.
  • the conductive particles are preferably present on the surface of the conductive carbon layer to be disposed on the MEA side (reaction surface side).
  • the separator 405 has an intermediate layer 456.
  • the intermediate layer 456 has a function of improving the adhesion between the metal base material 452 and the conductive carbon layer 454 and a function of preventing elution of ions from the metal base material 452.
  • the R value exceeds the upper limit value of the preferable range described above
  • the effect of providing the intermediate layer 456 is remarkably exhibited.
  • the intermediate layer is provided even when the R value is included in the preferred range described above. From another point of view, the above-described operational effects due to the installation of the intermediate layer 456 are remarkably exhibited even when the metal substrate 452 is made of aluminum or an alloy thereof.
  • the material constituting the intermediate layer 456 is not particularly limited as long as it provides the above-mentioned adhesion, but the same material as the intermediate layer 32 of the first embodiment can be used.
  • the thickness of the intermediate layer 456 is not particularly limited, but can be the same thickness as the intermediate layer 32 of the first embodiment.
  • the structure of the intermediate layer 456 is not particularly limited, but can be a columnar structure similar to the intermediate layer 32 of the first embodiment.
  • the thermal expansion coefficient ( ⁇ mid ) of the intermediate layer, the thermal expansion coefficient ( ⁇ sub ) of the metal base material, and the thermal expansion coefficient ( ⁇ c ) of the conductive carbon layer are expressed by Equation 2. It is preferable to satisfy this relationship.
  • the intermediate layer may be present on at least one surface of the metal substrate. However, when the conductive carbon layer exists only on one main surface of the metal substrate, the intermediate layer exists between the metal substrate and the conductive carbon layer. In addition, the conductive carbon layer may be present on both surfaces of the metal substrate as described above. In such a case, it is preferable that the intermediate layer is interposed between the metal base and both conductive carbon layers. When the intermediate layer exists only between the metal substrate and one of the conductive carbon layers, the intermediate layer is disposed on the MEA side in the PEFC and the conductive carbon layer and the metal substrate. It is preferable that it exists between.
  • the gas diffusion layers are composed of a gas diffusion substrate having a plurality of holes, and are disposed adjacent to the separators (anode separator 5a and cathode separator 5b).
  • the gas diffusion layer has a function of promoting diffusion of gas (fuel gas or oxidant gas) supplied through the gas flow paths (6a, 6c) of the separator to the catalyst layers (3a, 3b), and an electron conduction path.
  • gas diffusion layer As the gas diffusion layer according to the present embodiment, the gas diffusion layer described in the first embodiment can be used, or the gas diffusion layer described in the fourth embodiment can be used.
  • the method for producing a conductive member includes a step of forming a conductive carbon layer on at least one main surface of a metal substrate, a step of dispersing hydrophilic conductive particles on the surface of the conductive carbon layer, and the conductive property. And a step of disposing a gas diffusion layer so as to be in contact with the region where the particles are dispersed. Then, the conductive particles are dispersed by a sputtering method.
  • a stainless steel plate having a desired thickness is prepared as a constituent material of the metal substrate.
  • the surface of the prepared metal substrate is degreased and cleaned using an appropriate solvent.
  • the oxide film formed on the surface (both sides) of the metal substrate is removed.
  • the same method as in the first embodiment is used.
  • a conductive carbon layer is formed on the surface of the constituent material of the metal substrate subjected to the above-described treatment.
  • a conductive carbon layer can be formed by laminating a layer containing conductive carbon on a metal substrate at an atomic level using the above-described constituent material of the conductive carbon layer (for example, graphite) as a target. .
  • the adhesion between the interface between the conductive carbon layer and the metal substrate directly attached and the vicinity thereof is maintained for a long period of time due to intermolecular forces and the entry of a few carbon atoms.
  • the same technique as in the first embodiment can be used.
  • conductive particles are dispersed on the whole or a part of the surface of the conductive carbon layer subjected to the above treatment.
  • the conductive particles only have to be dispersed in a region in contact with the gas diffusion layer on the surface of the conductive carbon layer.
  • a mask may be formed and the conductive particles may be selectively dispersed in a desired portion.
  • a method of dispersing the conductive particles the same method as that of the conductive particles of the third embodiment can be used. Among these, it is preferable to use a sputtering method or a plating method.
  • the sputtering method When the sputtering method is used, a dispersed structure of conductive particles having high adhesion can be obtained. Moreover, it is preferable because the conductive particles can be dispersed continuously by simply changing the target following the formation (sputtering) of the conductive carbon layer.
  • the sputtering conditions are not particularly limited as long as the above-described conductive particle dispersion structure can be formed. However, it is preferable to apply a negative bias voltage to the metal substrate during sputtering. As an example, the magnitude of the applied voltage is preferably 50 to 500V, more preferably 100 to 300V. In addition, the specific forms such as other conditions are not particularly limited, and conventionally known knowledge is appropriately referred to.
  • the conductive particles can be dispersed with a high coverage. Further, since the process can be performed by the Roll-to-Roll method, mass production becomes possible.
  • the plating conditions are not particularly limited as long as the above-described conductive particle dispersion structure can be formed, and vary depending on the type and amount of the conductive particles used. For example, plating conditions are a current density of 0.25 to 5 A / dm 2 , a bath temperature of 45 to 55 ° C., and an electrodeposition time of about 10 seconds to about 100 minutes. However, since the deposition time varies depending on the size and shape of the counter electrode, it can be adjusted as appropriate. Under such conditions, a desired dispersed structure of conductive particles is easily formed.
  • the coverage and particle diameter of the conductive particles can be set to a desired range by previously grasping the relationship between the dispersion amount and conditions such as sputtering time or plating time in advance. .
  • the coverage varies depending on the material of the conductive carbon layer in which the conductive particles are dispersed and the method of dispersing the particles, it is necessary to grasp in advance the relationship between the material of the conductive carbon layer and the coating form There is.
  • the conductive particles are dispersed using a plating method, the conductive particles are adsorbed on the surface of the carbon, but the resin surface is adsorbed. Does not adsorb. For this reason, when such a composite material is used, it is necessary to control the coverage rate in consideration of the amount of resin contained in the composite material.
  • the conductive carbon layer 454 is formed on one or both main surfaces of the metal substrate 452.
  • a separator that is formed and has hydrophilic conductive particles 457 dispersed on the surface of the conductive carbon layer 454 is manufactured.
  • the intermediate layer is formed on at least one main surface of the metal substrate before the conductive carbon layer forming step described above.
  • the process to do is performed.
  • the method for forming the intermediate layer the same method as described above for the formation of the conductive carbon layer is employed.
  • a step of forming a conductive carbon layer and a step of dispersing conductive particles may be performed on the formed intermediate layer.
  • the method for forming the conductive carbon layer on the surface of the intermediate layer the same method as described above for the formation of the conductive carbon layer on the surface of the metal substrate is employed.
  • a conductive member formed by laminating the separator and the gas diffusion layer is obtained by laminating the gas diffusion base on the separator obtained by the above method.
  • the gas diffusion layer is laminated so that the gas diffusion layer is in contact with the region where the conductive particles are dispersed.
  • the conductive member of the present embodiment can be used as a conductive member constituting various fuel cells such as PAFC, MCFC, SOFC, and AFC in addition to PEFC, similarly to the conductive member of the first embodiment. Further, in addition to the conductive member, it is used for various applications that require both conductivity and corrosion resistance. In another preferred embodiment, the conductive member of the present embodiment is used in a wet environment and an energized environment. When used in such an environment, the effect of the present invention of achieving both conductivity and drainage remarkably appears.
  • Example V-1 A stainless steel plate (SUS316L) was prepared as a constituent material of the metal substrate constituting the separator.
  • the stainless steel plate has a thickness of 100 ⁇ m.
  • This stainless steel plate was subjected to ultrasonic cleaning in an ethanol solution for 3 minutes as a pretreatment.
  • the cleaned stainless steel plate was placed in a vacuum chamber, and ion bombardment with Ar gas was performed to remove the oxide film on the surface.
  • the vacuum degree of the vacuum chamber was about 10 ⁇ 3 Pa, and the Ar gas pressure was about 0.1 to 1 Pa.
  • the pretreatment and ion bombardment described above were both performed on both surfaces of the stainless steel plate.
  • an intermediate layer was formed by an unbalanced magnetron sputtering method. Specifically, using Cr as a target, an intermediate layer made of Cr was formed on both surfaces of the stainless steel plate while applying a negative bias voltage of 50 V to the stainless steel plate. The intermediate layer had a thickness of 0.2 ⁇ m.
  • a conductive carbon layer (polycrystalline graphite layer) was formed by the UBMS method.
  • conductive carbon layers were formed on the intermediate layers on both sides of the stainless steel plate while applying a negative bias voltage of 100 V to the stainless steel plate.
  • the thickness of the conductive carbon layer was 0.2 ⁇ m.
  • Example V-2 A separator (2) was produced in the same manner as in Example V-1, except that the sputtering time of the conductive particles (Au) was changed.
  • Example V-3 A separator (3) was produced in the same manner as in Example V-1, except that the sputtering time of the conductive particles (Au) was changed.
  • Example V-1 A separator (4) was produced in the same manner as in Example V-1, except that the conductive particles were not dispersed on the surface of the conductive carbon layer.
  • Example V-4 A separator (5) was produced in the same manner as in Example V-1, except that the graphite block (highly crystalline graphite) was used as it was as the conductive carbon layer.
  • Example V-2 A separator (6) was produced in the same manner as in Example V-4 described above, except that the conductive particles were not dispersed on the surface of the conductive carbon layer.
  • FIGS. 45 and 46 show SEM photographs of the surface of the conductive carbon layer in which the conductive particles (Au) in the separators (1) and (2) are dispersed. 45 and 46, it is confirmed that the conductive particles (Au) are uniformly dispersed on the surface of the conductive carbon layer. As for the separators other than the separator (4) in which the conductive particles and the metal oxide are not dispersed, the conductive particles (Au) are uniformly dispersed on the surface of the conductive carbon layer as in FIGS. 45 and 46. I confirmed.
  • the average particle diameter of the dispersed particles (conductive particles or metal oxide) present on the surface of each separator and the average distance between the dispersed particles were calculated.
  • the contact resistance is suppressed to a smaller value than in the comparative example, and the coverage is 1% or more. It can be seen that the contact resistance is significantly reduced. Furthermore, it was confirmed that the contact resistance can be suppressed to a very small value when the coverage is 10% or more.
  • the contact angle of water on the surface of the conductive carbon layer is suppressed to 70 ° or less compared to the case of the comparative example. You can see that Furthermore, it was confirmed that when the coverage is 10% or more, the value of the contact angle is decreased and the hydrophilicity is extremely improved.
  • Example V-1 when polycrystalline graphite was used (Example V-1), it was confirmed that the contact angle was reduced to 70 ° or less with a low coverage of about 4%. It was also confirmed that the contact angle was reduced to 70 ° or less at a low coverage of about 4% even when a graphite block was used (Example V-4).
  • the R value of the conductive carbon layer was measured. Specifically, first, the Raman spectrum of the conductive carbon layer was measured using a microscopic Raman spectrometer. Then, 1300 ⁇ 1400 cm peak intensity of the bands (D-band) located -1 (I D), the peak area ratio of the peak intensity (I G) of band (G-band) located 1500 ⁇ 1600 cm -1 ( I D / I G ) was calculated and used as the R value. The results obtained are shown in Table 6 below.
  • the R values of the conductive carbon layers in the separators produced in Examples V-1 to V-3 and Comparative Example V-1 were all 1.3 or more.
  • the R values of the conductive carbon layers in the separators produced in Example V-4 and Comparative Example V-2 were both less than 1.3. From Table 6, when the separator prepared in Example V-1 having an R value of 1.3 or more was used, an example in which the R value prepared under the same conditions except for the R value was less than 1.3. Compared with the case of V-4, it was confirmed that the contact resistance can be suppressed to a smaller value.
  • Japanese Patent Application No. 2008-300313 (Application Date: November 25, 2008), Japanese Patent Application No. 2008-301309 (Application Date: November 26, 2008), Japanese Patent Application No. 2008-303217 (Application Date: November 2008) 27), Japanese Patent Application No. 2008-303219 (Application Date: November 27, 2008), Japanese Patent Application No. 2008-303223 (Application Date: November 27, 2008) and Japanese Patent Application No. 2009-142600 (Application Date: The entire contents of June 15, 2009) are incorporated herein.
  • the conductive member of the present invention by ensuring a conductive path from one surface of the conductive carbon layer to the other surface, it is possible to sufficiently improve the corrosion resistance while sufficiently ensuring excellent conductivity. A member is provided.

Abstract

Provided is a conductive member having a conductive structure formed by: a base (31, 152, 252, 352, 452), a conductive carbon layer (33, 155, 254, 354, 454) containing a conductive carbon and arranged on at least one surface of the base; and an intermediate layer (32, 154, 256, 356, 456) sandwiched between the base and the conductive carbon layer.  The intensity ratio R (ID/IG) between the D band peak intensity (ID) and the G band peak intensity (IG) measured in the conductive carbon layer by the Raman scattering spectroscopy is 1.3 or above.

Description

導電部材及びこれを用いた固体高分子形燃料電池Conductive member and polymer electrolyte fuel cell using the same
　本発明は、導電部材及びこれを用いた固体高分子形燃料電池に関する。 The present invention relates to a conductive member and a polymer electrolyte fuel cell using the same.
　固体高分子形燃料電池（ＰＥＦＣ）は、発電機能を発揮する複数の単セルが積層された構造を有する。当該単セルはそれぞれ、（１）高分子電解質膜と、（２）これを挟持する一対の触媒層と、（３）これらを挟持し、供給ガスを分散させるための一対のガス拡散層（ＧＤＬ）と、を備えた膜電極接合体（ＭＥＡ）を有する。そして、個々の単セルが有するＭＥＡは、セパレータを介して隣接する単セルのＭＥＡと電気的に接続される。このようにして単セルが積層されることにより、燃料電池スタックが構成される。そして、この燃料電池スタックは、種々の用途に使用可能な発電手段として機能する。このようなスタックにおいて、セパレータは、上述したように、隣接する単セル同士を電気的に接続する機能を発揮する。これに加えて、ＭＥＡと対向するセパレータの表面にはガス流路が設けられるのが通常である。当該ガス流路は、アノード及びカソードに燃料ガス及び酸化剤ガスをそれぞれ供給するためのガス供給手段として機能する。 The polymer electrolyte fuel cell (PEFC) has a structure in which a plurality of single cells exhibiting a power generation function are stacked. Each of the single cells includes (1) a polymer electrolyte membrane, (2) a pair of catalyst layers sandwiching the polymer electrolyte membrane, and (3) a pair of gas diffusion layers (GDL) for sandwiching them and dispersing the supply gas. And a membrane electrode assembly (MEA). And MEA which each single cell has is electrically connected with MEA of an adjacent single cell through a separator. Thus, a fuel cell stack is comprised by laminating | stacking a single cell. The fuel cell stack functions as power generation means that can be used for various applications. In such a stack, the separator exhibits a function of electrically connecting adjacent single cells as described above. In addition to this, a gas flow path is usually provided on the surface of the separator facing the MEA. The gas flow path functions as a gas supply means for supplying fuel gas and oxidant gas to the anode and the cathode, respectively.
　ＰＥＦＣの発電メカニズムを簡単に説明すると、ＰＥＦＣの運転時には、アノード側に燃料ガス（例えば水素ガス）が供給され、カソード側に酸化剤ガス（例えば大気、酸素）が供給される。その結果、アノード及びカソードのそれぞれにおいて、下記反応式で表される電気化学反応が進行し、電気が生み出される。 Briefly explaining the power generation mechanism of PEFC, during operation of PEFC, fuel gas (for example, hydrogen gas) is supplied to the anode side, and oxidant gas (for example, air or oxygen) is supplied to the cathode side. As a result, in each of the anode and the cathode, an electrochemical reaction represented by the following reaction formula proceeds to generate electricity.
Figure JPOXMLDOC01-appb-M000001
Figure JPOXMLDOC01-appb-M000001
　導電性が要求される燃料電池用セパレータの構成材料としては、従来、金属、カーボン及び導電性樹脂などが知られている。これらのうち、カーボンセパレータや導電性樹脂セパレータでは、ガス流路形成後の強度をある程度確保すべく、厚さを比較的大きく設定する必要がある。その結果、これらのセパレータを用いた燃料電池スタックの全体の厚さも大きくなってしまう。そして、スタックの大型化は、特に小型化が求められている車載用ＰＥＦＣなどにおいては、好ましくない。 Conventionally, metals, carbon, conductive resins, and the like are known as constituent materials for fuel cell separators that require electrical conductivity. Among these, in the carbon separator and the conductive resin separator, it is necessary to set the thickness relatively large in order to secure the strength after forming the gas flow path to some extent. As a result, the overall thickness of the fuel cell stack using these separators also increases. The increase in the size of the stack is not preferable especially in an in-vehicle PEFC that requires a reduction in size.
　一方、金属セパレータは強度が比較的大きいため、厚さを比較的小さくすることが可能である。また、導電性にも優れることから、金属セパレータを用いるとＭＥＡとの接触抵抗を低減させるという利点もある。その反面、金属材料では腐食による導電性の低下や、これに伴うスタックの出力の低下という問題が生じる場合がある。よって、金属セパレータでは、その優れた導電性を確保しつつ、耐食性をも向上させることが求められている。 On the other hand, since the metal separator has a relatively high strength, the thickness can be made relatively small. Moreover, since it is excellent also in electroconductivity, when a metal separator is used, there also exists an advantage that contact resistance with MEA is reduced. On the other hand, metal materials may have problems such as a decrease in conductivity due to corrosion and a decrease in stack output. Therefore, the metal separator is required to improve the corrosion resistance while ensuring its excellent conductivity.
　ここで、特許文献１には、金属セパレータの金属基材の一方の面に、Ｔｉ等の金属層やその炭化物層を形成し、該金属層やその炭化物層上にグラファイト化された炭素からなる炭素層を形成する技術が開示されている。 Here, in Patent Document 1, a metal layer such as Ti or a carbide layer thereof is formed on one surface of a metal substrate of a metal separator, and is composed of graphitized carbon on the metal layer or the carbide layer. A technique for forming a carbon layer is disclosed.
　また、特許文献２には、金属セパレータの基材と導電性薄膜との間に該基材の酸化皮膜を形成し、金属元素や半金属元素からなる中間層を形成する技術が開示されている。 Patent Document 2 discloses a technique in which an oxide film of a base material is formed between a base material of a metal separator and a conductive thin film to form an intermediate layer made of a metal element or a metalloid element. .
　さらに、特許文献３には、金属酸化物を複合化させて含有する炭素系膜が基材上に形成されたセパレータが開示されている。 Furthermore, Patent Document 3 discloses a separator in which a carbon-based film containing a composite of metal oxide is formed on a substrate.
特開２００６－２８６４５７号公報JP 2006-286457 A 特開２００４－１８５９９８号公報JP 2004-185998 A 特開２００７－１３４１０７号公報JP 2007-134107 A
　従来技術に係る、炭素層を有する燃料電池セパレータにおいて、当該炭素層の有する結晶構造は様々である。炭素層の結晶構造が異なると、これに起因してセパレータ自体の耐食性や導電性も変動する。ただし、いずれにしても従来技術のセパレータは、たとえ炭素層の配置のような表面処理が施されたものであっても、未だ十分な耐食性・導電性が確保されているとはいえない。また、特許文献２に記載の技術において、基材表面に配置される酸化皮膜はそれ自身が絶縁性の高い層である。このため、セパレータの厚さ方向の導電性が低下してしまう。さらに、特許文献３に記載の技術において、炭素膜に含まれる金属酸化物は絶縁性を示すため、セパレータの厚さ方向の導電性が低下したり、ガス拡散層との間の接触抵抗が増加してしまう。 In the fuel cell separator having a carbon layer according to the prior art, the crystal structure of the carbon layer is various. When the crystal structure of the carbon layer is different, the corrosion resistance and conductivity of the separator itself vary due to this. However, in any case, even if the separator of the prior art is subjected to a surface treatment such as arrangement of a carbon layer, it cannot be said that sufficient corrosion resistance and conductivity are still ensured. Moreover, in the technique described in Patent Document 2, the oxide film disposed on the surface of the base material itself is a highly insulating layer. For this reason, the electrical conductivity in the thickness direction of the separator is lowered. Furthermore, in the technique described in Patent Document 3, since the metal oxide contained in the carbon film exhibits insulating properties, the conductivity in the thickness direction of the separator is reduced or the contact resistance with the gas diffusion layer is increased. Resulting in.
　本発明は、このような従来技術の有する課題に鑑みてなされたものである。そして、その目的は、導電部材において、優れた導電性を十分に確保しつつ、耐食性をより一層向上させた導電部材、その製造方法及び導電部材を用いた固体高分子形燃料電池を提供することにある。 The present invention has been made in view of such problems of the conventional technology. The object of the present invention is to provide a conductive member having sufficiently improved corrosion resistance while sufficiently ensuring excellent conductivity in the conductive member, a manufacturing method thereof, and a polymer electrolyte fuel cell using the conductive member. It is in.
　本発明の第一の態様に係る導電部材は、基材と、前記基材の少なくとも一方の表面に位置し、さらに導電性炭素を含む導電性炭素層と、前記基材と導電性炭素層との間に介在する中間層と、を有した導電構造体を備え、前記導電性炭素層において、ラマン散乱分光分析により測定されたＤバンドピーク強度（ＩＤ）とＧバンドピーク強度（ＩＧ）との強度比Ｒ（ＩＤ／ＩＧ）が１．３以上であることを特徴とする。 The conductive member according to the first aspect of the present invention includes a base material, a conductive carbon layer that is located on at least one surface of the base material, and further includes conductive carbon, and the base material and the conductive carbon layer. And an intermediate layer interposed between the D band peak intensity (I D ) and G band peak intensity (I G ) measured by Raman scattering spectroscopy in the conductive carbon layer. And the intensity ratio R (I D / I G ) is 1.3 or more.
　本発明の第二の態様に係る固体高分子形燃料電池は、前記導電部材を備える。 The polymer electrolyte fuel cell according to the second aspect of the present invention includes the conductive member.
図１は、第一実施形態における導電部材（セパレータ）を用いた固体高分子形燃料電池のセルユニットの基本構成を示す断面概略図である。FIG. 1 is a schematic cross-sectional view showing a basic configuration of a cell unit of a polymer electrolyte fuel cell using a conductive member (separator) in the first embodiment. 図２は、図１のセパレータの金属基材と該基材上に形成された処理層の構成を模式的に示す断面図である。FIG. 2 is a cross-sectional view schematically showing the configuration of the metal substrate of the separator of FIG. 1 and the treatment layer formed on the substrate. 図３は、図１のうち、金属セパレータの表面を示す断面概略図である。FIG. 3 is a schematic cross-sectional view showing the surface of the metal separator in FIG. 図４Ａは、図１のセパレータにおける金属基材の両面に、中間層及び導電性炭素層が設けられた構成を模式的に示す断面図である。4A is a cross-sectional view schematically showing a configuration in which an intermediate layer and a conductive carbon layer are provided on both surfaces of a metal substrate in the separator of FIG. 図４Ｂは、中間層及び導電性炭素層の一形態を示した拡大図である。FIG. 4B is an enlarged view showing one embodiment of the intermediate layer and the conductive carbon layer. 図４Ｃは、中間層及び導電性炭素層の他の形態を示した拡大図である。FIG. 4C is an enlarged view showing another form of the intermediate layer and the conductive carbon layer. 図５Ａは、Ｒ＝１．０～１．２の導電性炭素層を有する導電部材（導電部材Ａ）の断面をＴＥＭにより観察した写真（倍率：４０万倍）である。FIG. 5A is a photograph (magnification: 400,000 times) of a cross section of a conductive member (conductive member A) having a conductive carbon layer with R = 1.0 to 1.2 observed by TEM. 図５Ｂは、Ｒ＝１．６の導電性炭素層を有する導電部材（導電部材Ｂ）の断面をＴＥＭにより観察した写真（倍率：４０万倍）である。FIG. 5B is a photograph (magnification: 400,000 times) of a cross section of a conductive member (conductive member B) having a conductive carbon layer with R = 1.6 observed by TEM. 図６Ａは、ラマン散乱分光分析の回転異方性測定における、平均ピークの３回対称パターンを示す模式図である。FIG. 6A is a schematic diagram showing a three-fold symmetry pattern of an average peak in the measurement of rotational anisotropy in Raman scattering spectroscopic analysis. 図６Ｂは、ラマン散乱分光分析の回転異方性測定における、平均ピークの２回対称パターンを示す模式図である。FIG. 6B is a schematic diagram showing a two-fold symmetry pattern of an average peak in rotational anisotropy measurement of Raman scattering spectroscopic analysis. 図６Ｃは、ラマン散乱分光分析の回転異方性測定において、平均ピークの対称性を示さないパターンを示す模式図である。FIG. 6C is a schematic diagram showing a pattern that does not show the symmetry of the average peak in the measurement of rotational anisotropy of Raman scattering spectroscopic analysis. 図７Ａは、導電部材Ｂを測定サンプルとして用い、当該サンプルの回転角をそれぞれ０°、６０°、及び１８０°としたときのラマンスペクトルを示すグラフである。FIG. 7A is a graph showing a Raman spectrum when the conductive member B is used as a measurement sample, and the rotation angles of the sample are 0 °, 60 °, and 180 °, respectively. 図７Ｂは、導電部材Ｂについての回転異方性測定の平均ピークを示すグラフである。FIG. 7B is a graph showing the average peak of rotational anisotropy measurement for conductive member B. 図８は、スパッタリング法で、バイアス電圧及び成膜方式を変化させることにより導電性炭素層のビッカース硬度を異ならせた導電部材における、導電性炭素層のビッカース硬度と導電性炭素層のｓｐ３比の値との関係を示す図である。FIG. 8 shows the Vickers hardness of the conductive carbon layer and the sp 3 ratio of the conductive carbon layer in the conductive member in which the Vickers hardness of the conductive carbon layer is varied by changing the bias voltage and the film formation method by sputtering. It is a figure which shows the relationship with the value of. 図９は、Ｒ値が１．３以上であるものの、水素原子の含有量が異なる導電性炭素層を有する導電部材について、接触抵抗を測定した結果を示すグラフである。FIG. 9 is a graph showing the results of measurement of contact resistance for conductive members having conductive carbon layers having different R atom values but having different hydrogen atom contents. 図１０は、本発明の実施形態に係る燃料電池スタックを搭載した車両の概念図である。FIG. 10 is a conceptual diagram of a vehicle equipped with a fuel cell stack according to an embodiment of the present invention. 図１１は、実施例において接触抵抗を測定するのに用いた測定装置の概要を示す模式図である。FIG. 11 is a schematic diagram showing an outline of a measuring apparatus used for measuring contact resistance in Examples. 図１２Ａは、実施例I－１～I－７及び比較例I－１～I－５において作製した導電部材について、浸漬試験の前後に接触抵抗の測定を行った結果を示すグラフである。FIG. 12A is a graph showing the results of measurement of contact resistance before and after the immersion test for the conductive members produced in Examples I-1 to I-7 and Comparative Examples I-1 to I-5. 図１２Ｂは、実施例I－８及び実施例I－９において作製した導電部材について、浸漬試験の前後に接触抵抗の測定を行った結果を示すグラフである。FIG. 12B is a graph showing the results of measurement of contact resistance before and after the immersion test for the conductive members produced in Example I-8 and Example I-9. 図１３は、本発明の実施形態に係る導電部材を適用した燃料電池スタックを示す概略図である。FIG. 13 is a schematic view showing a fuel cell stack to which a conductive member according to an embodiment of the present invention is applied. 図１４は、図１３の燃料電池スタックの斜視図である。14 is a perspective view of the fuel cell stack of FIG. 図１５ａ及び図１５ｂは、実施例I－９及び実施例I－８の表面を観察したＳＥＭ写真である。15a and 15b are SEM photographs of the surfaces of Example I-9 and Example I-8. 図１６ａ及び図１６ｂは、図１５ａ及び図１５ｂのＳＥＭ写真を拡大したものである。16a and 16b are enlarged views of the SEM photographs of FIGS. 15a and 15b. 図１７ａ及び図１７ｂは、実施例I－９及び実施例I－８の断面を観察したＴＥＭ写真である。FIGS. 17a and 17b are TEM photographs of the cross sections of Example I-9 and Example I-8. 図１８ａ及び図１８ｂは、実施例I－９及び実施例I－８の断面を観察したＳＥＭ写真である。18a and 18b are SEM photographs observing the cross sections of Example I-9 and Example I-8. 図１９は、中間層及び導電性炭素層をスパッタリング法で成膜するための製造装置を示した平面概略図である。FIG. 19 is a schematic plan view showing a manufacturing apparatus for forming an intermediate layer and a conductive carbon layer by sputtering. 図２０は、中間層及び導電性炭素層をアークイオンプレーティング法で成膜するための製造装置を示した平面概略図である。FIG. 20 is a schematic plan view showing a manufacturing apparatus for forming an intermediate layer and a conductive carbon layer by an arc ion plating method. 図２１は、第二実施形態における導電部材（セパレータ）の表面の構成を示す断面概略図である。FIG. 21 is a schematic cross-sectional view showing the configuration of the surface of the conductive member (separator) in the second embodiment. 図２２Ａは、参考例II－１で作製した緻密バリア層の断面を、ＴＥＭにより画像解析を行った結果を示す写真である。FIG. 22A is a photograph showing the result of image analysis of the cross section of the dense barrier layer produced in Reference Example II-1 by TEM. 図２２Ｂは、参考例II－２で作製した中間層の断面を、ＴＥＭにより画像解析を行った結果を示す写真である。FIG. 22B is a photograph showing the result of image analysis of the cross section of the intermediate layer produced in Reference Example II-2 by TEM. 図２３Ａは、参考例II－１で作製した緻密バリア層の表面を、ＳＥＭにより画像解析を行った結果を示す写真である。FIG. 23A is a photograph showing a result of image analysis of the surface of the dense barrier layer produced in Reference Example II-1 by SEM. 図２３Ｂは、参考例II－２で作製した中間層の表面を、ＳＥＭにより画像解析を行った結果を示す写真である。FIG. 23B is a photograph showing the result of image analysis performed on the surface of the intermediate layer prepared in Reference Example II-2 by SEM. 図２３Ｃは、参考例II－１で作製した緻密バリア層を、図２３Ａより詳細に画像解析した結果を示すＳＥＭ写真である。FIG. 23C is an SEM photograph showing the result of image analysis of the dense barrier layer produced in Reference Example II-1 in more detail than in FIG. 23A. 図２３Ｄは、参考例II－２で作製した中間層を、図２３Ｂより詳細に画像解析した結果を示すＳＥＭ写真である。FIG. 23D is a SEM photograph showing the result of image analysis of the intermediate layer produced in Reference Example II-2 in more detail than FIG. 23B. 図２４は、実施例II－２で作製した導電部材の断面を、ＴＥＭにより画像解析を行った結果を示す写真である。FIG. 24 is a photograph showing the result of image analysis of the cross section of the conductive member produced in Example II-2 by TEM. 図２５は、第三実施形態における導電部材（セパレータ）の表面の構成を示す断面概略図である。FIG. 25 is a schematic cross-sectional view showing the configuration of the surface of the conductive member (separator) in the third embodiment. 図２６は、８０℃、ｐＨ４の硫酸水溶液に１００時間浸漬した金属基材（ＳＵＳ３１６Ｌ）のオージェ電子分光法による元素濃度の計測結果を示すグラフである。FIG. 26 is a graph showing the measurement results of element concentration by Auger electron spectroscopy of a metal substrate (SUS316L) immersed in an aqueous sulfuric acid solution at 80 ° C. and pH 4 for 100 hours. 図２７は、酸化被膜を形成させた金属基材の表面に導電性粒子を被覆させた部材における、導電性粒子の被覆率と接触抵抗との関係を示すグラフであるFIG. 27 is a graph showing the relationship between the coverage of conductive particles and contact resistance in a member in which conductive particles are coated on the surface of a metal substrate on which an oxide film is formed. 図２８は、第三実施形態に係る導電性粒子及び柱状性材料を含む導電部材を模式的に示した断面図である。FIG. 28 is a cross-sectional view schematically showing a conductive member including conductive particles and a columnar material according to the third embodiment. 図２９は、ＡＥＳによリ測定された、耐久試験を行う前のサンプル（III－１）の積層方向の元素濃度プロファイルを示す図面である。FIG. 29 is a drawing showing the element concentration profile in the stacking direction of the sample (III-1) measured by AES and before the endurance test. 図３０は、ＡＥＳによリ測定された、耐久試験を行った後のサンプル（III－１）の積層方向の元素濃度プロファイルを示す図面である。FIG. 30 is a drawing showing the element concentration profile in the stacking direction of sample (III-1) after the endurance test, measured by AES. 図３１は、ＡＥＳによリ測定された、耐久試験を行った後のサンプル（III－２）の積層方向の元素濃度プロファイルを示す図面である。FIG. 31 is a drawing showing the element concentration profile in the stacking direction of sample (III-2) after the endurance test, measured by AES. 図３２は、ＡＥＳによリ測定された、耐久試験を行った後のサンプル（III－３）の積層方向の元素濃度プロファイルを示す図面である。FIG. 32 is a drawing showing the element concentration profile in the stacking direction of sample (III-3) after the endurance test, measured by AES. 図３３は、ＡＥＳによリ測定された、耐久試験を行った後のサンプル（III－４）の積層方向の元素濃度プロファイルを示す図面である。FIG. 33 is a drawing showing the element concentration profile in the stacking direction of sample (III-4) after the endurance test, measured by AES. 図３４は、第四実施形態に係るガス拡散層の表面の構成を示す断面概略図である。FIG. 34 is a schematic cross-sectional view showing the configuration of the surface of the gas diffusion layer according to the fourth embodiment. 図３５は、多孔質材料層の表面を微視的に表した概略図である。FIG. 35 is a schematic view microscopically showing the surface of the porous material layer. 図３６は、ＰＡＮ系炭素繊維の各製造工程における繊維の変化を示す概略図である。FIG. 36 is a schematic view showing changes in fibers in each manufacturing process of PAN-based carbon fibers. 図３７は、スパッタリング法を用いた、中間層や導電性炭素層の成膜装置を示す概略図である。FIG. 37 is a schematic diagram showing an intermediate layer or conductive carbon layer deposition apparatus using a sputtering method. 図３８は、一般的なＰＡＮ系炭素繊維の製造工程及び第四実施形態におけるＰＡＮ系炭素繊維の製造工程を示す図である。FIG. 38 is a diagram showing a general PAN-based carbon fiber manufacturing process and a PAN-based carbon fiber manufacturing process in the fourth embodiment. 図３９は、実施例IV－１及び各比較例IV－１，IV－２で得られたＧＤＬとセパレータとの接触抵抗の測定方法を示す図である。FIG. 39 is a diagram showing a method for measuring the contact resistance between the GDL obtained in Example IV-1 and Comparative Examples IV-1 and IV-2 and the separator. 図４０は、表５に示す実施例IV－１の接触抵抗に関する結果に対応するグラフである。FIG. 40 is a graph corresponding to the results regarding contact resistance of Example IV-1 shown in Table 5. 図４１は、ＡＥＳの面マッピング及び画像解析によって算出した、導電性の炭素及びＡｕの面積比に対する水の静的接触角の測定結果を示すグラフである。FIG. 41 is a graph showing the measurement result of the static contact angle of water with respect to the area ratio of conductive carbon and Au, calculated by AES surface mapping and image analysis. 図４２は、導電性炭素層の表面にＡｕを分散させつつスパッタした場合の抵抗低減効果を示すグラフである。FIG. 42 is a graph showing the resistance reduction effect when sputtering is performed while Au is dispersed on the surface of the conductive carbon layer. 図４３は、第五実施形態に係る導電部材の構成を示す断面概略図である。FIG. 43 is a schematic cross-sectional view showing the configuration of the conductive member according to the fifth embodiment. 図４４Ａは、炭素繊維又は炭素粒子から構成されるガス拡散基体と、導電性粒子が分散した導電性炭素層との接触領域を模式的に示す断面図である。FIG. 44A is a cross-sectional view schematically showing a contact region between a gas diffusion base composed of carbon fibers or carbon particles and a conductive carbon layer in which conductive particles are dispersed. 図４４Ｂは、多孔性金属から構成されるガス拡散基体と、導電性粒子が分散した導電性炭素層との接触領域を模式的に示す断面図である。FIG. 44B is a cross-sectional view schematically showing a contact region between a gas diffusion base composed of a porous metal and a conductive carbon layer in which conductive particles are dispersed. 図４５は、セパレータ（１）における導電性粒子（Ａｕ）が分散した導電性炭素層の表面を示すＳＥＭ写真である。FIG. 45 is a SEM photograph showing the surface of the conductive carbon layer in which conductive particles (Au) are dispersed in the separator (1). 図４６は、セパレータ（２）における導電性粒子（Ａｕ）が分散された導電性炭素層の表面を示すＳＥＭ写真である。FIG. 46 is an SEM photograph showing the surface of the conductive carbon layer in which conductive particles (Au) in the separator (2) are dispersed. 図４７Ａは、ＡＥＳによリ測定された、セパレータ（２）の積層方向の元素濃度プロファイルを示す図面である。FIG. 47A is a drawing showing an element concentration profile in the stacking direction of the separator (2), measured by AES. 図４７Ｂは、ＡＥＳによリ測定された、セパレータ（４）の積層方向の元素濃度プロファイルを示す図面である。FIG. 47B is a drawing showing an element concentration profile in the stacking direction of the separator (4), measured by AES. 図４８は、実施例及び比較例において作製したセパレータについて、接触抵抗の測定を行った結果を示すグラフである。FIG. 48 is a graph showing the results of measurement of contact resistance for the separators produced in the examples and comparative examples. 図４９は、実施例及び比較例において作製したセパレータについて、接触角の測定を行った結果を示すグラフである。FIG. 49 is a graph showing the results of measuring the contact angle for the separators produced in the examples and comparative examples.
［第一実施形態］
　以下、本発明の第一実施形態に係る導電部材、その製造方法及び固体高分子形燃料電池について、図面に基づき詳細に説明する。なお、本発明は、以下の実施形態のみに制限されない。また、図面の寸法比率は、説明の都合上誇張されており、実際の比率とは異なる場合がある。 [First embodiment]
Hereinafter, a conductive member, a manufacturing method thereof, and a polymer electrolyte fuel cell according to a first embodiment of the present invention will be described in detail with reference to the drawings. In addition, this invention is not restrict | limited only to the following embodiment. In addition, the dimensional ratios in the drawings are exaggerated for convenience of explanation, and may be different from the actual ratios.
　本実施形態の導電部材（導電構造体）は、金属基材と、前記金属基材の少なくとも一方の表面に位置する、導電性炭素を含む導電性炭素層とを有する。そして、前記導電性炭素層のラマン散乱分光分析により測定されたＤバンドピーク強度（ＩＤ）とＧバンドピーク強度（ＩＧ）との強度比Ｒ（ＩＤ／ＩＧ）が１．３以上である。また、本実施形態の導電部材として好ましくは、金属基材と、前記金属基材上に中間層とが設けられ、前記中間層上に導電性炭素層が被覆されている。そして、前記中間層が柱状構造を有しており、前記導電部材の最表面に突起状粒子が存在していることが望ましい。 The conductive member (conductive structure) of this embodiment has a metal base material and a conductive carbon layer containing conductive carbon located on at least one surface of the metal base material. And the intensity ratio R (I D / I G ) between the D band peak intensity (I D ) and the G band peak intensity (I G ) measured by the Raman scattering spectroscopic analysis of the conductive carbon layer is 1.3 or more. It is. In addition, the conductive member of the present embodiment is preferably provided with a metal base and an intermediate layer on the metal base, and the conductive carbon layer is coated on the intermediate layer. And it is desirable for the said intermediate | middle layer to have a columnar structure, and for the projecting particle to exist in the outermost surface of the said electrically-conductive member.
　従来技術の導電性炭素層を有する燃料電池セパレータにおいて、当該導電性炭素層が有する結晶構造は様々であった。そのため、こうした導電性炭素層の結晶構造が異なると、これに起因してセパレータ自体の耐食性や導電性も大きく変動する。言い換えれば、燃料電池を安定的に制御するのが困難となる。ただし、いずれにしても、従来技術により提供される金属セパレータは、たとえ導電性炭素層の配置のような表面処理が施されたものであっても、実用に耐えることができる十分な耐食性・導電性が確保されているとはいえなかった。また、金属セパレータの基板上に導電性炭素膜を形成する場合、密着性を確保するために金属層やその炭化物層等の中間層を設けても、中間層の結晶構造の制御は行われていなかった。そのため、基材の防食機能と導電性炭素膜の緻密性が不十分で、金属基材にまで水分子が浸入し、基材の腐食が促進されることで接触抵抗が増加するという問題が生じていた。また、上記特許文献２の技術では、基材表面に配置される酸化皮膜はそれ自身が絶縁性の高い層である。このため、セパレータの厚さ方向の導電性が低下するという問題が生じていた。 In the conventional fuel cell separator having a conductive carbon layer, the crystalline structure of the conductive carbon layer varies. Therefore, if the crystal structure of such a conductive carbon layer is different, the corrosion resistance and conductivity of the separator itself greatly vary due to this. In other words, it becomes difficult to stably control the fuel cell. In any case, however, the metal separator provided by the prior art has sufficient corrosion resistance and conductivity that can withstand practical use even if it has been subjected to a surface treatment such as the arrangement of a conductive carbon layer. It could not be said that the sex was secured. In addition, when a conductive carbon film is formed on a substrate of a metal separator, the crystal structure of the intermediate layer is controlled even if an intermediate layer such as a metal layer or its carbide layer is provided to ensure adhesion. There wasn't. As a result, the anticorrosion function of the base material and the denseness of the conductive carbon film are insufficient, water molecules penetrate into the metal base material, and the corrosion resistance of the base material is promoted, resulting in an increase in contact resistance. It was. Moreover, in the technique of the said patent document 2, the oxide film arrange | positioned on the base-material surface itself is a layer with high insulation. For this reason, the problem that the electroconductivity of the thickness direction of a separator fell has arisen.
　そこで、本実施形態では、金属セパレータ（導電部材）にアルミニウム等の腐食しやすい金属基材を適用する際、その防食機能を高める方策として、中間層の柱状構造結晶を太くしている。その際に現れる特徴のひとつとして、中間層、更には導電部材の最表面に突起形状が存在する。一方、従来の製法では、突起形状が存在しない。 Therefore, in this embodiment, when a metal base material such as aluminum, which is easily corroded, is applied to the metal separator (conductive member), the columnar structure crystal of the intermediate layer is thickened as a measure for enhancing the anticorrosion function. As one of the features appearing at that time, there is a protrusion shape on the outermost surface of the intermediate layer and further the conductive member. On the other hand, in the conventional manufacturing method, there is no protrusion shape.
　本発明は、導電性炭素層における隙間や欠陥を低減することのできる画期的なものである。さらに最表層に存在する突起状粒子は中間層の柱状構造の柱径の発達に起因するものであり、最表層の隙間の数が減少し、水の侵入を抑制する機能を付与することができる。その結果、金属基材の防食効果を高めることができ、アルミニウムのような軽量で安価な反面、腐食しやすい金属の場合でも、セパレータの基材として長期間安定して適用できる。即ち、中間層の柱状構造の柱径を大きくすることで、中間層の隙間、及びその上に存在する導電性炭素膜の欠陥を減らし、水の進入を防止することで各界面での酸化を抑制し、接触抵抗の増加を抑制することができるものといえる。中間層の柱状構造は、好ましくは柱状結晶である。以下の説明では、中間層の柱状構造としてベストである柱状結晶を用いて説明している部分もあるが、必ずしも柱状結晶のみに制限されるものではなく、柱状構造に広く適用し得るものである。 The present invention is an epoch-making thing that can reduce gaps and defects in the conductive carbon layer. Further, the protruding particles present in the outermost layer are caused by the development of the column diameter of the columnar structure of the intermediate layer, and the number of gaps in the outermost layer is reduced, and a function of suppressing water intrusion can be provided. . As a result, the anticorrosion effect of the metal substrate can be enhanced, and while being lightweight and inexpensive like aluminum, it can be stably applied as a separator substrate for a long time even in the case of a metal that is easily corroded. That is, by increasing the column diameter of the columnar structure of the intermediate layer, the gaps in the intermediate layer and the defects of the conductive carbon film existing thereon are reduced, and oxidation at each interface is prevented by preventing water from entering. It can be said that the increase in contact resistance can be suppressed. The columnar structure of the intermediate layer is preferably a columnar crystal. In the following description, there is a portion described using the columnar crystal that is the best as the columnar structure of the intermediate layer, but it is not necessarily limited to the columnar crystal and can be widely applied to the columnar structure. .
　図１は、本実施形態の導電部材の一例である金属セパレータを用いた燃料電池の基本構成、詳しくは固体高分子型燃料電池（ＰＥＦＣ）のセルユニットの基本構成を模式的に示す断面図である。図２は、図１の金属セパレータの基材表面に形成された層の概要を示す部分断面図である。 FIG. 1 is a cross-sectional view schematically showing a basic configuration of a fuel cell using a metal separator, which is an example of a conductive member of the present embodiment, specifically a basic configuration of a cell unit of a polymer electrolyte fuel cell (PEFC). is there. FIG. 2 is a partial cross-sectional view showing an outline of a layer formed on the surface of the base material of the metal separator of FIG.
　図１に示す燃料電池（ＰＥＦＣ）のセルユニット１では、まず、固体高分子電解質膜２と、その両面にこれを挟持する一対の触媒層３（アノード触媒層３ａ及びカソード触媒層３ｂ）とを有する。そして、それら固体高分子電解質膜２と触媒層３（３ａ、３ｂ）との積層体はさらに、一対のガス拡散層４（アノードガス拡散層４ａ及びカソードガス拡散層４ｂ）により挟持されている。このように、固体高分子電解質膜２、一対の触媒層（３ａ、３ｂ）及び一対のガス拡散層（４ａ、４ｂ）は、積層された状態で膜電極接合体（ＭＥＡ）９を構成する。 In the cell unit 1 of the fuel cell (PEFC) shown in FIG. 1, first, a solid polymer electrolyte membrane 2 and a pair of catalyst layers 3 (an anode catalyst layer 3a and a cathode catalyst layer 3b) sandwiching the solid polymer electrolyte membrane 2 on both sides thereof are provided. Have. The laminate of the solid polymer electrolyte membrane 2 and the catalyst layer 3 (3a, 3b) is further sandwiched between a pair of gas diffusion layers 4 (anode gas diffusion layer 4a and cathode gas diffusion layer 4b). Thus, the solid polymer electrolyte membrane 2, the pair of catalyst layers (3a, 3b), and the pair of gas diffusion layers (4a, 4b) constitute a membrane electrode assembly (MEA) 9 in a stacked state.
　ＰＥＦＣのセルユニット１において、ＭＥＡ９はさらに、導電性を有する一対の金属セパレータ５（アノードセパレータ５ａ及びカソードセパレータ５ｂ）により挟持されて、セルユニット１を構成している。図１において、金属セパレータ５ａ，５ｂは、ＭＥＡ９の両側に位置するように図示されている。ただし、複数のＭＥＡ９が積層されてなるスタックでは、金属セパレータ５は、隣接するＰＥＦＣのための金属セパレータ５としても用いられるのが一般的である（図１３、１４参照）。換言すれば、燃料電池スタックにおいて、ＭＥＡ９は、金属セパレータ５を介して順次積層されることにより、スタックを構成することとなる。なお、実際の燃料電池スタックにおいては、金属セパレータ５ａ、５ｂと固体高分子電解質膜２との間や、セルユニット１とこれと隣接する他のセルユニット１との間にガスシール部が配置されるが、図１、２ではこれらの記載を省略する（図１３、１４参照）。 In the PEFC cell unit 1, the MEA 9 is further sandwiched by a pair of conductive metal separators 5 (an anode separator 5a and a cathode separator 5b) to constitute the cell unit 1. In FIG. 1, the metal separators 5 a and 5 b are illustrated so as to be located on both sides of the MEA 9. However, in a stack in which a plurality of MEAs 9 are stacked, the metal separator 5 is generally used also as a metal separator 5 for an adjacent PEFC (see FIGS. 13 and 14). In other words, in the fuel cell stack, the MEAs 9 are sequentially stacked via the metal separator 5 to constitute a stack. In an actual fuel cell stack, a gas seal portion is disposed between the metal separators 5a and 5b and the solid polymer electrolyte membrane 2, or between the cell unit 1 and another cell unit 1 adjacent thereto. However, these descriptions are omitted in FIGS. 1 and 2 (see FIGS. 13 and 14).
　金属セパレータ５（５ａ、５ｂ）は、例えば、厚さ０．５ｍｍ以下の薄板にプレス処理を施すことで図１、２及び１３に示すような凹凸状の形状に成形することにより得られる。金属セパレータ５のＭＥＡ９側から見た凸部はＭＥＡ９と接触している。これにより、ＭＥＡ９との電気的な接続が確保される。また、金属セパレータ５のＭＥＡ９側から見た凹部（金属セパレータ５の有する凹凸状の形状に起因して生じる金属セパレータ５とＭＥＡ９との間の空間）は、ＰＥＦＣ１の運転時にガスを流通させるためのガス流路として機能する。具体的には、アノードセパレータ５ａのガス流路５ａａには燃料ガス５ａｇを流通させ、カソードセパレータ５ｂのガス流路５ｂｂには酸化剤ガス５ｂｇを流通させる。燃料ガス５ａｇとしては、例えば、水素や水素含有ガスなどを用いることができ、酸化剤ガス５ｂｇとしては、例えば、空気やＯ２含有ガスなどを用いることができる。 The metal separator 5 (5a, 5b) is obtained, for example, by forming a concavo-convex shape as shown in FIGS. 1, 2, and 13 by subjecting a thin plate having a thickness of 0.5 mm or less to a press treatment. The convex part seen from the MEA 9 side of the metal separator 5 is in contact with the MEA 9. Thereby, the electrical connection with MEA9 is ensured. In addition, a recess (a space between the metal separator 5 and the MEA 9 generated due to the uneven shape of the metal separator 5) as viewed from the MEA 9 side of the metal separator 5 is used to circulate gas during the operation of the PEFC 1. Functions as a gas flow path. Specifically, the fuel gas 5ag is circulated through the gas flow path 5aa of the anode separator 5a, and the oxidant gas 5bg is circulated through the gas flow path 5bb of the cathode separator 5b. As the fuel gas 5ag, for example, hydrogen or a hydrogen-containing gas can be used, and as the oxidant gas 5bg, for example, air or an O 2 -containing gas can be used.
　一方、金属セパレータ５のＭＥＡ９側とは反対の側から見た凹部は、ＰＥＦＣ１の運転時にＰＥＦＣを冷却するための冷媒８ｗを流通させるための冷媒流路８とされる。冷媒８ｗとしては、例えば、冷却水や水を用いることができる。さらに、金属セパレータ５には通常、マニホールド（図示せず）が設けられる。このマニホールドは、スタックを構成した際に各セルユニット１を連結するための連結手段として機能する。このような構成とすることで、燃料電池スタックの機械的強度を確保することができる（図１３、１４参照）。なお、実際の燃料電池では、金属セパレータ５と電解質膜２の端部の間、及び燃料電池のセルユニット１と隣り合う別のセルユニット１との間でガスシールを配置するが、本図では省略する。 On the other hand, the recess viewed from the side opposite to the MEA 9 side of the metal separator 5 serves as a refrigerant flow path 8 for circulating the refrigerant 8w for cooling the PEFC during operation of the PEFC 1. As the refrigerant 8w, for example, cooling water or water can be used. Further, the metal separator 5 is usually provided with a manifold (not shown). This manifold functions as a connection means for connecting the cell units 1 when a stack is formed. With such a configuration, the mechanical strength of the fuel cell stack can be ensured (see FIGS. 13 and 14). In an actual fuel cell, a gas seal is disposed between the metal separator 5 and the end of the electrolyte membrane 2 and between another cell unit 1 adjacent to the cell unit 1 of the fuel cell. Omitted.
　以上のように、金属セパレータ５は、各ＭＥＡ９を直列に電気的に接続する機能に加えて、燃料ガス５ａｇ及び酸化剤ガス５ｂｇ並びに冷媒８ｗといった異なる流体を流すガス流路５ａａ、５ｂｂや冷媒流路８やマニホールドを備え、さらにはスタックの機械的強度を保つといった機能も有する。また、電解質膜２には、通常、パーフルオロスルホン酸型の膜を使用することから、電解質膜から溶出する種々の酸性イオンと電池に投入される加湿ガスの影響により、電池内は湿潤の弱酸性腐食環境下にある。このため、図２に示すように、金属セパレータ５の表面処理は、導電性だけでなく耐食性の両方が必要になる。金属セパレータ５の金属基材６上に配置される表面処理のための層７は、腐食条件の厳しい反応面に実施されることは必須であるが、反応面７ａとは裏の冷却面７ｂにおいても冷媒（冷却水）８ｗの種類や環境によって同様の処理が必要となる。 As described above, in addition to the function of electrically connecting each MEA 9 in series, the metal separator 5 has gas flow paths 5aa and 5bb that flow different fluids such as the fuel gas 5ag, the oxidant gas 5bg, and the refrigerant 8w, and the refrigerant flow. A path 8 and a manifold are provided, and further, there is a function of maintaining the mechanical strength of the stack. In addition, since a perfluorosulfonic acid type membrane is usually used as the electrolyte membrane 2, the inside of the battery is weakly wet due to various acidic ions eluted from the electrolyte membrane and the humidified gas introduced into the battery. Under an acidic corrosive environment. For this reason, as shown in FIG. 2, the surface treatment of the metal separator 5 requires not only conductivity but also corrosion resistance. The surface treatment layer 7 disposed on the metal substrate 6 of the metal separator 5 is essential to be applied to the reaction surface having severe corrosion conditions. However, the reaction surface 7a is different from the cooling surface 7b. The same processing is required depending on the type and environment of the refrigerant (cooling water) 8w.
　図３は、金属セパレータ５の表面部分の一形態を示す断面図である。本実施形態において、金属セパレータ５を構成する導電部材は、金属基材３１と、導電性炭素層３３とを有する。そして、これらの間には、中間層３２が介在している。なお、セルユニット１において、金属セパレータ５は、導電性炭素層３３がＭＥＡ９側に位置するように配置される。 FIG. 3 is a cross-sectional view showing one form of the surface portion of the metal separator 5. In the present embodiment, the conductive member constituting the metal separator 5 includes a metal base 31 and a conductive carbon layer 33. An intermediate layer 32 is interposed between them. In the cell unit 1, the metal separator 5 is arranged so that the conductive carbon layer 33 is located on the MEA 9 side.
　図４Ａは、金属セパレータの金属基材表面に形成される各層の構成・配置を示す部分断面図であって、表面処理のための各層に求められる機能を解説するための簡略図である。図４Ｂは、図４Ａの一部を拡大し、太い柱状結晶構造を有している中間層及び最表面に突起状粒子が存在している導電性炭素層の構成をより明確にした拡大図である。図４Ｃは、セパレータの金属基材、細い針状結晶構造を有してなる中間層及び最表面に突起状粒子がない導電性炭素層の構成をより明確にした拡大図である。図４Ｂ中のＨ１、Ｈ２、Ｈ３、・・は導電性炭素層３３の最表面の突起状粒子の高さ（突起高さ）を示し、Ｗ１、Ｗ２、Ｗ３、・・は中間層３２にある柱状結晶構造の太さ（柱径、幅）を示す。図４Ｃ中の符号３３ｂは導電性炭素層３３の最表面の突起状粒子を示す。 FIG. 4A is a partial cross-sectional view showing the configuration and arrangement of each layer formed on the surface of the metal substrate of the metal separator, and is a simplified diagram for explaining functions required for each layer for surface treatment. FIG. 4B is an enlarged view in which a part of FIG. 4A is enlarged to further clarify the configuration of an intermediate layer having a thick columnar crystal structure and a conductive carbon layer in which protruding particles are present on the outermost surface. is there. FIG. 4C is an enlarged view that clarifies the configuration of the metal base material of the separator, the intermediate layer having a thin acicular crystal structure, and the conductive carbon layer having no protruding particles on the outermost surface. In FIG. 4B, H 1 , H 2 , H 3 ,... Indicate the height of the protruding particles on the outermost surface of the conductive carbon layer 33 (projection height), and W 1 , W 2 , W 3 ,. Indicates the thickness (column diameter, width) of the columnar crystal structure in the intermediate layer 32. Reference numeral 33 b in FIG. 4C indicates the protruding particles on the outermost surface of the conductive carbon layer 33.
　図４Ａに示す実施形態においても、金属セパレータ５を構成する導電部材は、金属基材３１（図２の符号６）と、導電性炭素層３３（図２の符号７の一部：外側部）とを有する。そして、これらの間には、中間層３２（図２の符号７の一部：内側部）が介在している。 Also in the embodiment shown in FIG. 4A, the conductive members constituting the metal separator 5 are the metal base 31 (reference numeral 6 in FIG. 2) and the conductive carbon layer 33 (part of reference numeral 7 in FIG. 2: outer portion). And have. And between these, the intermediate | middle layer 32 (a part of code | symbol 7 of FIG. 2: inside part) is interposing.
　図４Ａ～４Ｃに示すように、金属セパレータ５の断面構成としては、金属セパレータ５の金属基材３１の両主面（表面）に中間層３２と最表層の導電性炭素層３３が配置されている。金属基材３１に例えばＳＵＳ３１６Ｌのような耐食性に優れたステンレスを用いた場合、金属基材３１自体が燃料電池内の腐食環境下に耐えられるため、防食を目的とした中間層３２の要求はそれほど厳しくない。しかしながら、本発明者の試験結果から、薄肉化、低コスト化をより強く推し進めるべく、ステンレスよりも薄肉軽量化に優れるアルミニウムを金属基材３１とする場合、アルミニウム自体が耐食性に乏しいため、中間層３２の結晶構造を制御することによって、上記課題（防食手段等）が解決し得ることを見出したものである。 As shown in FIGS. 4A to 4C, the metal separator 5 has a cross-sectional configuration in which an intermediate layer 32 and an outermost conductive carbon layer 33 are disposed on both main surfaces (surfaces) of the metal base 31 of the metal separator 5. Yes. When stainless steel with excellent corrosion resistance such as SUS316L is used for the metal substrate 31, the metal substrate 31 itself can withstand the corrosive environment in the fuel cell. Not strict. However, from the test results of the present inventor, in order to further promote thinning and cost reduction, when the metal base 31 is made of aluminum that is thinner and lighter than stainless steel, since the aluminum itself has poor corrosion resistance, the intermediate layer It has been found that the above problems (such as anticorrosion means) can be solved by controlling the crystal structure of 32.
　金属セパレータ５の金属基材３１材料の腐食は、電池内の弱酸（酸性度）と金属セパレータ５の表面電位に左右される。このためアルミニウムを金属セパレータ５の金属基材３１とした場合、酸性度や電位に対する防食が必要となる。しかしながら、腐食自体は水の存在によって始めて発生するため、金属基材３１のアルミニウムが水とできるだけ接することの無いような表面処理が腐食の根本を対策することとなり、その効果は非常に大きい。このため、上記最表層の導電性炭素層３３にピンホール等の欠陥が生じた場合でも、中間層３２の結晶構造を制御することで、中間層３２以下のセパレータ内部への水の浸透を抑制することができ、所期の優れた電池性能を長期間安定して保持することができる。以下、本実施形態の金属セパレータ５の各構成要素について詳述する。 The corrosion of the metal base material 31 of the metal separator 5 depends on the weak acid (acidity) in the battery and the surface potential of the metal separator 5. For this reason, when aluminum is used as the metal substrate 31 of the metal separator 5, it is necessary to prevent corrosion against acidity and potential. However, since the corrosion itself occurs for the first time due to the presence of water, a surface treatment in which the aluminum of the metal base 31 is not in contact with water as much as possible will take a countermeasure against the corrosion, and the effect is very great. For this reason, even if defects such as pinholes occur in the outermost conductive carbon layer 33, the penetration of water into the separator below the intermediate layer 32 is suppressed by controlling the crystal structure of the intermediate layer 32. Therefore, the expected excellent battery performance can be stably maintained for a long time. Hereinafter, each component of the metal separator 5 of this embodiment is explained in full detail.
　［金属基材］
　金属基材３１は、金属セパレータ５を構成する導電部材の主層であり、導電性及び機械的強度の確保に寄与する。 [Metal base material]
The metal substrate 31 is a main layer of a conductive member that constitutes the metal separator 5, and contributes to ensuring conductivity and mechanical strength.
　金属基材３１の構成材料としては、鉄、チタン、銅及びアルミニウム並びにこれらの合金が挙げられる。これらの材料は、機械的強度、汎用性、コストパフォーマンス又は加工容易性などの観点から好ましく用いられる。ここで、鉄合金にはステンレスが含まれる。なかでも、金属基材３１はステンレス、アルミニウム又はアルミニウム合金から構成されることが好ましい。ステンレスを金属基材３１として用いると、ガス拡散層（ＧＤＬ）４の構成材料であるガス拡散基体との接触面の導電性が十分に確保される。その結果、たとえリブ肩部の膜の隙間などに水分が浸入したとしても、ステンレスから構成される金属基材３１自体に生じる酸化皮膜の耐食性により、耐久性が維持される。ここでＧＤＬは、ＧＤＬ４（４ａ、４ｂ）に面圧が直接かかる部分（金属セパレータ５と接触部分；リブ部分）と、直接はかからない部分（接触していない部分；流路部分）とからなり、上記リブ肩部は、上記金属セパレータ５と接触部分の肩部をさす。 Examples of the constituent material of the metal substrate 31 include iron, titanium, copper, aluminum, and alloys thereof. These materials are preferably used from the viewpoints of mechanical strength, versatility, cost performance, or processability. Here, the iron alloy includes stainless steel. Especially, it is preferable that the metal base material 31 is comprised from stainless steel, aluminum, or aluminum alloy. When stainless steel is used as the metal substrate 31, the conductivity of the contact surface with the gas diffusion substrate that is a constituent material of the gas diffusion layer (GDL) 4 is sufficiently ensured. As a result, even if moisture enters the gaps between the rib shoulder film and the like, the durability is maintained by the corrosion resistance of the oxide film formed on the metal base 31 itself made of stainless steel. Here, the GDL is composed of a portion where the surface pressure is directly applied to the GDL 4 (4a, 4b) (the metal separator 5 and the contact portion; a rib portion) and a portion that is not directly applied (the portion that is not in contact; the flow path portion). The rib shoulder portion refers to the shoulder portion of the contact portion with the metal separator 5.
　ステンレスとしては、オーステナイト系、マルテンサイト系、フェライト系、オーステナイト・フェライト系、析出硬化系などが挙げられる。オーステナイト系としては、日本工業規格に規定されているＳＵＳ２０１、ＳＵＳ２０２、ＳＵＳ３０１、ＳＵＳ３０２、ＳＵＳ３０３、ＳＵＳ３０４、ＳＵＳ３０５、ＳＵＳ３１６（Ｌ）、ＳＵＳ３１７が挙げられる。オーステナイト・フェライト系としては、ＳＵＳ３２９Ｊ１が挙げられる。マルテンサイト系としては、ＳＵＳ４０３、ＳＵＳ４２０が挙げられる。フェライト系としては、ＳＵＳ４０５、ＳＵＳ４３０、ＳＵＳ４３０ＬＸが挙げられる。析出硬化系としては、ＳＵＳ６３０が挙げられる。なかでも、ＳＵＳ３０４、ＳＵＳ３１６等のオーステナイト系ステンレスを用いることがより好ましい。また、ステンレス中の鉄の含有率は、好ましくは６０～８４質量％であり、より好ましくは６５～７２質量％である。さらに、ステンレス中のクロムの含有率は、好ましくは１６～２０質量％であり、より好ましくは１６～１８質量％である。 Examples of stainless steel include austenite, martensite, ferrite, austenite / ferrite, and precipitation hardening. Examples of austenite include SUS201, SUS202, SUS301, SUS302, SUS303, SUS304, SUS305, SUS316 (L), and SUS317, which are defined in Japanese Industrial Standards. Examples of the austenite-ferrite type include SUS329J1. Examples of the martensite system include SUS403 and SUS420. Examples of the ferrite type include SUS405, SUS430, and SUS430LX. Examples of the precipitation hardening system include SUS630. Among these, it is more preferable to use austenitic stainless steel such as SUS304 and SUS316. The content of iron in the stainless steel is preferably 60 to 84% by mass, more preferably 65 to 72% by mass. Furthermore, the chromium content in the stainless steel is preferably 16 to 20% by mass, more preferably 16 to 18% by mass.
　一方、アルミニウム合金としては、純アルミニウム系、及びアルミニウム・マンガン系、アルミニウム・マグネシウム系などが挙げられる。アルミニウム合金中におけるアルミニウム以外の元素については、アルミニウム合金として一般に使用可能なものであれば特に制限されない。例えば、銅、マンガン、ケイ素、マグネシウム、亜鉛及びニッケルなどがアルミニウム合金に含まれる。アルミニウム合金の具体例として、純アルミニウム系としては日本工業規格に規定されているＡ１０５０、Ａ１０５０Ｐが挙げられ、アルミニウム・マンガン系としてはＡ３００３Ｐ、Ａ３００４Ｐが挙げられ、アルミニウム・マグネシウム系としてはＡ５０５２Ｐ、Ａ５０８３Ｐが挙げられる。一方で、セパレータには機械的な強度や成形性も求められるため、上記の合金種に加えて、合金の調質も適宜選択される。なお、金属基材３１がチタンやアルミニウムの単体から構成される場合、当該チタンやアルミニウムの純度は、好ましくは９５質量％以上であり、より好ましくは９７質量％以上であり、さらに好ましくは９９質量％以上である。 On the other hand, examples of the aluminum alloy include pure aluminum, aluminum / manganese, and aluminum / magnesium. The elements other than aluminum in the aluminum alloy are not particularly limited as long as they are generally usable as an aluminum alloy. For example, copper, manganese, silicon, magnesium, zinc and nickel are included in the aluminum alloy. Specific examples of the aluminum alloy include A1050 and A1050P specified in Japanese Industrial Standards as pure aluminum, A3003P and A3004P as aluminum / manganese, and A5052P and A5083P as aluminum / magnesium. Can be mentioned. On the other hand, since the separator is also required to have mechanical strength and formability, the alloy tempering is appropriately selected in addition to the above alloy types. In addition, when the metal base material 31 is comprised from the simple substance of titanium or aluminum, the purity of the said titanium or aluminum becomes like this. Preferably it is 95 mass% or more, More preferably, it is 97 mass% or more, More preferably, it is 99 mass % Or more.
　金属基材３１の厚さは、加工容易性及び機械的強度、並びにセパレータ５自体を薄膜化することによる電池のエネルギー密度の向上等の観点より、５０μｍ～５００μｍがこのましい。金属基材の厚さは、より好ましくは８０μｍ～３００μｍであり、さらに好ましくは８０μｍ～２００μｍである。特に、ステンレスを用いた場合の金属基材３１の厚さは、好ましくは８０μｍ～１５０μｍである。一方、アルミニウムを用いた場合の金属基材３１の厚さは、好ましくは１００μｍ～３００μｍである。上記範囲内の場合、金属セパレータ５として十分な強度を有しながらも、加工容易性に優れ、好適な薄さを達成可能である。 The thickness of the metal substrate 31 is preferably 50 μm to 500 μm from the viewpoint of ease of processing and mechanical strength, and improvement of the energy density of the battery by making the separator 5 itself a thin film. The thickness of the metal substrate is more preferably 80 μm to 300 μm, still more preferably 80 μm to 200 μm. In particular, the thickness of the metal substrate 31 when stainless steel is used is preferably 80 μm to 150 μm. On the other hand, the thickness of the metal substrate 31 when aluminum is used is preferably 100 μm to 300 μm. When it is within the above range, the metal separator 5 has sufficient strength, but is excellent in workability and can achieve a suitable thickness.
　なお、例えば燃料電池用セパレータ５等の構成材料として十分な強度を提供するという観点から、金属基材３１は、ガス遮断性が高い材料から構成されることが好ましい。燃料電池のセパレータ５はセル同士を仕切る役割を担っているため、セパレータ５を挟んで両側で異なるガスが流れる構成となる（図１３参照）。したがって、隣り合うガスの混合やガス流量の変動をなくすという観点から、金属基材３１はガス遮断性が高いほど好ましい。 Note that, for example, from the viewpoint of providing sufficient strength as a constituent material for the fuel cell separator 5 or the like, the metal base 31 is preferably made of a material having a high gas barrier property. Since the separator 5 of the fuel cell plays a role of partitioning cells, different gas flows on both sides of the separator 5 (see FIG. 13). Therefore, from the viewpoint of eliminating the mixing of adjacent gases and the fluctuation of the gas flow rate, the metal base 31 is preferably as the gas barrier property is higher.
　［導電性炭素層］
　導電性炭素層３３は、導電性炭素を含む層である。この層の存在によって、金属セパレータ５を構成する導電部材の導電性を確保しつつ、金属基材３１のみの場合と比較して耐食性が改善される。 [Conductive carbon layer]
The conductive carbon layer 33 is a layer containing conductive carbon. The presence of this layer improves the corrosion resistance as compared with the case of only the metal substrate 31 while ensuring the conductivity of the conductive member constituting the metal separator 5.
　本実施形態において、導電性炭素層３３は、ラマン散乱分光分析により測定される、Ｄバンドピーク強度（ＩＤ）とＧバンドピーク強度（ＩＧ）との強度比Ｒ（ＩＤ／ＩＧ）により規定される。具体的には、強度比Ｒ（ＩＤ／ＩＧ）が１．３以上である。以下、当該構成要件について、より詳細に説明する。 In the present embodiment, the conductive carbon layer 33 has an intensity ratio R (I D / I G ) between the D band peak intensity (I D ) and the G band peak intensity (I G ) measured by Raman scattering spectroscopy. It is prescribed by. Specifically, the intensity ratio R (I D / I G ) is 1.3 or more. Hereinafter, the configuration requirement will be described in more detail.
　炭素材料をラマン分光法により分析すると、通常１３５０ｃｍ－１付近及び１５８４ｃｍ－１付近にピークが生じる。結晶性の高いグラファイトは、１５８４ｃｍ－１付近にシングルピークを有し、このピークは通常、「Ｇバンド」と称される。一方、結晶性が低くなる、つまり結晶構造欠陥が増し、グラファイト構造が乱れるにつれて、１３５０ｃｍ－１付近のピークが現れてくる。このピークは通常、「Ｄバンド」と称される。なお、ダイヤモンドのピークは厳密には１３３３ｃｍ－１であり、上記Ｄバンドとは区別される。Ｄバンドピーク強度（ＩＤ）とＧバンドピーク強度（ＩＧ）との強度比Ｒ（ＩＤ／ＩＧ）は、炭素材料のグラファイトクラスタサイズやグラファイト構造の乱れ具合（結晶構造欠陥性）、ｓｐ２結合比率などの指標として用いられる。すなわち、本実施形態においては、Ｒ値を導電性炭素層３３の接触抵抗の指標とすることができ、さらに導電性炭素層３３の導電性を制御する膜質パラメータとして用いることができる。 When the carbon material is analyzed by Raman spectroscopy, peaks are usually generated around 1350 cm −1 and 1584 cm −1 . Highly crystalline graphite has a single peak near 1584 cm −1 , and this peak is usually referred to as the “G band”. On the other hand, as crystallinity decreases, that is, crystal structure defects increase and the graphite structure is disturbed, a peak near 1350 cm −1 appears. This peak is usually referred to as the “D band”. Strictly speaking, the peak of diamond is 1333 cm −1 and is distinguished from the D band. The intensity ratio R (I D / I G ) between the D band peak intensity (I D ) and the G band peak intensity (I G ) is the graphite cluster size of the carbon material and the disorder of the graphite structure (crystal structure defect), Used as an index such as sp 2 bond ratio. That is, in the present embodiment, the R value can be used as an index of the contact resistance of the conductive carbon layer 33 and can be used as a film quality parameter for controlling the conductivity of the conductive carbon layer 33.
　Ｒ（ＩＤ／ＩＧ）値は、顕微ラマン分光器を用いて、炭素材料のラマンスペクトルを計測することにより算出される。具体的には、Ｄバンドと呼ばれる１３００～１４００ｃｍ－１のピーク強度（ＩＤ）と、Ｇバンドと呼ばれる１５００～１６００ｃｍ－１のピーク強度（ＩＧ）との相対的強度比（ピーク面積比（ＩＤ／ＩＧ））を算出することにより求められる。 The R (I D / I G ) value is calculated by measuring the Raman spectrum of the carbon material using a microscopic Raman spectrometer. Specifically, the peak intensity of 1300 ~ 1400 cm -1 called the D band (I D), the relative intensity ratio of the peak intensity of 1500 ~ 1600 cm -1 called the G band (I G) (peak area ratio ( I D / I G )).
　上述したように、本実施形態において、Ｒ値は１．３以上である。また、当該Ｒ値は、好ましくは１．４～２．０であり、より好ましくは１．４～１．９であり、さらに好ましくは１．５～１．８である。このＲ値が１．３以上であれば、燃料電池の積層方向の導電性が十分に確保された導電性炭素層３３が得られる。また、Ｒ値が２．０以下であれば、グラファイト成分の減少を抑制することができる。さらに、導電性炭素層３３自体の内部応力の増大をも抑制でき、下地である金属基材３１（中間層３２）との密着性を一層向上させることができる。 As described above, in this embodiment, the R value is 1.3 or more. The R value is preferably 1.4 to 2.0, more preferably 1.4 to 1.9, and further preferably 1.5 to 1.8. If the R value is 1.3 or more, the conductive carbon layer 33 in which the conductivity in the stacking direction of the fuel cell is sufficiently secured can be obtained. Moreover, if R value is 2.0 or less, the reduction | decrease of a graphite component can be suppressed. Furthermore, the increase in internal stress of the conductive carbon layer 33 itself can be suppressed, and the adhesion with the metal base material 31 (intermediate layer 32) which is the base can be further improved.
　なお、本実施形態のようにＲ値を１．３以上とすることにより上述の作用効果が得られるメカニズムは、以下のように推定されている。ただし、以下の推定メカニズムは本発明の技術的範囲を限定することはない。 In addition, the mechanism by which the above-mentioned effect is acquired by making R value 1.3 or more like this embodiment is estimated as follows. However, the following estimation mechanism does not limit the technical scope of the present invention.
　上述したように、Ｄバンドピーク強度が大きくなる（すなわち、Ｒ値が大きくなる）ことは、グラファイト構造における結晶構造欠陥の増加を意味する。換言すれば、ほぼｓｐ２炭素のみからなる高結晶性グラファイトにおいてｓｐ３炭素が増加することを意味する。ここで、Ｒ＝１．０～１．２の導電性炭素層を有する導電部材Ａの断面を透過型電子顕微鏡（ＴＥＭ）により観察した写真（倍率：４０万倍）を図５Ａに示す。同様に、Ｒ＝１．６の導電性炭素層を有する導電部材Ｂの断面をＴＥＭにより観察した写真（倍率：４０万倍）を図５Ｂに示す。なお、これらの導電部材Ａ及び導電部材Ｂは、金属基材３１としてはＳＵＳ３１６Ｌを用い、この表面上にＣｒからなる中間層３２（厚さ：０．２μｍ）及び導電性炭素層３３（厚さ：０．２μｍ）をスパッタリング法によって順次形成することにより作製した。また、導電部材Ａにおける導電性炭素層３３の作製時において金属基材３１に対して印加したバイアス電圧は０Ｖであり、導電部材Ｂにおける導電性炭素層３３の作製時において金属基材３１に対して印加したバイアス電圧は－１４０Ｖであった。 As described above, increasing the D-band peak intensity (that is, increasing the R value) means an increase in crystal structure defects in the graphite structure. In other words, it means that the sp 3 carbon increases in the highly crystalline graphite consisting of only sp 2 carbon. Here, a photograph (magnification: 400,000 times) of a cross section of the conductive member A having a conductive carbon layer with R = 1.0 to 1.2 observed with a transmission electron microscope (TEM) is shown in FIG. 5A. Similarly, the photograph (magnification: 400,000 times) which observed the cross section of the electrically-conductive member B which has the conductive carbon layer of R = 1.6 by TEM is shown to FIG. 5B. The conductive member A and the conductive member B use SUS316L as the metal base 31 and have an intermediate layer 32 (thickness: 0.2 μm) made of Cr and a conductive carbon layer 33 (thickness) on the surface. : 0.2 μm) was sequentially formed by a sputtering method. Further, the bias voltage applied to the metal base material 31 when the conductive carbon layer 33 in the conductive member A is manufactured is 0 V, and the metal base material 31 is applied when the conductive carbon layer 33 in the conductive member B is manufactured. The applied bias voltage was -140V.
　そして、図５Ｂに示すように、導電部材Ｂの導電性炭素層は、多結晶グラファイトの構造を有することがわかる。つまり、多数のグラファイトクラスタ３３ｃが存在していることがわかる。一方で、図５Ａに示す導電部材Ａの導電性炭素層においては、このような多結晶グラファイトの構造は確認できない。 As shown in FIG. 5B, it can be seen that the conductive carbon layer of the conductive member B has a structure of polycrystalline graphite. That is, it can be seen that there are many graphite clusters 33c. On the other hand, such a structure of polycrystalline graphite cannot be confirmed in the conductive carbon layer of the conductive member A shown in FIG. 5A.
　ここで、「多結晶グラファイト」とは、微視的にはグラフェン面（六角網面）が積層した異方性のグラファイト結晶構造（グラファイトクラスタ）を有するが、巨視的には多数の当該グラファイト構造が集合した等方性結晶体である。したがって、多結晶グラファイトは、ダイヤモンド様カーボン（ＤＬＣ；Ｄｉａｍｏｎｄ－Ｌｉｋｅ　Ｃａｒｂｏｎ）の一種であるということもできる。通常、単結晶グラファイトは、ＨＯＰＧ（高配向熱分解黒鉛）に代表されるような、巨視的にみてもグラフェン面が積層された乱れのない構造を示す。一方、多結晶グラファイトにおいては、個々のクラスタとしてグラファイト構造が存在しており、乱層構造を有している。Ｒ値を上述の値に制御することで、この乱れ具合（グラファイトクラスタ量、サイズ）が適度に確保され、導電性炭素層３３の一方の面から他方の面への導電パスが確保される。その結果、金属基材３１に加えて、導電性炭素層３３を別途設けたことによる導電性の低下が防止されると考えられる。さらに導電性炭素層３３に加えて、金属基材３１と導電性炭素層３３との間に中間層３２を設け、さらにその結晶構造を制御することにより、優れた導電性を十分に確保しつつ、接触抵抗の増加を抑制することができる。 Here, “polycrystalline graphite” microscopically has an anisotropic graphite crystal structure (graphite cluster) in which graphene surfaces (hexagonal network surfaces) are laminated, but macroscopically, a large number of such graphite structures. Is an isotropic crystal. Accordingly, it can be said that polycrystalline graphite is a kind of diamond-like carbon (DLC). Normally, single crystal graphite has a disordered structure in which graphene surfaces are laminated even when viewed macroscopically, as represented by HOPG (highly oriented pyrolytic graphite). On the other hand, in polycrystalline graphite, a graphite structure exists as an individual cluster, and has a turbostratic structure. By controlling the R value to the above-described value, this degree of disorder (graphite cluster amount, size) is appropriately ensured, and a conductive path from one surface of the conductive carbon layer 33 to the other surface is ensured. As a result, it is considered that a decrease in conductivity due to the separate provision of the conductive carbon layer 33 in addition to the metal substrate 31 is prevented. Furthermore, in addition to the conductive carbon layer 33, an intermediate layer 32 is provided between the metal substrate 31 and the conductive carbon layer 33, and further, the crystal structure is controlled, thereby sufficiently ensuring excellent conductivity. An increase in contact resistance can be suppressed.
　多結晶グラファイトにおいて、グラファイトクラスタを構成するｓｐ２炭素原子の結合によりグラフェン面が形成されていることから、当該グラフェン面の面方向に導電性が確保される。また、多結晶グラファイトは実質的に炭素原子のみから構成され、比表面積が小さく、結合した官能基の量も少ない。このため、多結晶グラファイトは酸性水等による腐食に対して優れた耐性を有する。なお、カーボンブラック等の粉末においても、１次粒子を形成しているのはグラファイトクラスタの集合体である場合が多く、これにより導電性が発揮される。しかしながら、個々の粒子が分離しているため、表面に形成されている官能基が多く、酸性水等による腐食が生じやすい。また、カーボンブラックにより導電性炭素層３３を成膜しても、保護膜としての緻密性に欠けるという問題もある。 In polycrystalline graphite, since the graphene surface is formed by the bonding of sp 2 carbon atoms constituting the graphite cluster, conductivity is ensured in the plane direction of the graphene surface. Polycrystalline graphite is substantially composed of only carbon atoms, has a small specific surface area, and a small amount of bonded functional groups. For this reason, polycrystalline graphite has excellent resistance to corrosion by acidic water or the like. In addition, even in powders such as carbon black, primary particles are often formed by aggregates of graphite clusters, thereby exhibiting electrical conductivity. However, since the individual particles are separated, there are many functional groups formed on the surface, and corrosion due to acidic water or the like is likely to occur. Further, even when the conductive carbon layer 33 is formed with carbon black, there is a problem that the denseness as a protective film is lacking.
　ここで、本実施形態の導電性炭素層３３が多結晶グラファイトから構成される場合、多結晶グラファイトを構成するグラファイトクラスタのサイズは特に制限されない。一例を挙げると、グラファイトクラスタの平均直径は、好ましくは１ｎｍ～５０ｎｍ程度であり、より好ましくは２ｎｍ～１０ｎｍである。グラファイトクラスタの平均直径がこのような範囲内の値であると、多結晶グラファイトの結晶構造を維持しつつ、導電性炭素層３３の厚膜化を防止することができる。ここで、グラファイトクラスタの「直径」とは、当該クラスタの輪郭線上の任意の２点間の距離のうち、最大の距離を意味する。また、グラファイトクラスタの平均直径の値は、ＳＥＭやＴＥＭなどの観察手段を用い、数～数十視野中に観察されるクラスタの直径の平均値として算出される。 Here, when the conductive carbon layer 33 of the present embodiment is made of polycrystalline graphite, the size of the graphite cluster constituting the polycrystalline graphite is not particularly limited. As an example, the average diameter of the graphite cluster is preferably about 1 nm to 50 nm, more preferably 2 nm to 10 nm. When the average diameter of the graphite cluster is within such a range, it is possible to prevent the conductive carbon layer 33 from being thickened while maintaining the crystal structure of the polycrystalline graphite. Here, the “diameter” of the graphite cluster means the maximum distance among the distances between any two points on the contour line of the cluster. Further, the average diameter value of the graphite clusters is calculated as an average value of the diameters of the clusters observed in several to several tens of fields using an observation means such as SEM or TEM.
　さらに、本実施形態では、図４Ｂ等に示すように、中間層３２の表面上において、導電性炭素層３３の一部を構成し、２００ｎｍ～５００ｎｍの径を持つ突起状粒子３３ａを持つのが望ましい。より好ましくは上記導電部材の最表面において、２００ｎｍ～５００ｎｍの径を持つ突起状粒子３３ａと、５０ｎｍ～１００ｎｍの微小粒子３３ｂとが混在していることが特に望ましい（実施例I－８参照）。但し、本実施形態では、図４Ｃに示すように、上記導電部材の最表面において、２００ｎｍ～５００ｎｍの径を持つ突起状粒子３３ａを持たなくても良い。より詳しくは上記導電部材の最表面において、２００ｎｍ～５００ｎｍの径を持つ突起状粒子３３ａが存在せず、５０ｎｍ～１００ｎｍの微小粒子３３ｂのみで構成された導電性炭素層３３からなるものであっても良い。かかる構成でも、導電性炭素層３３の強度比Ｒが１．３以上であれば、本発明の所期の目的を達成することができる（実施例I－９参照）。 Furthermore, in the present embodiment, as shown in FIG. 4B and the like, a part of the conductive carbon layer 33 is formed on the surface of the intermediate layer 32, and has protruding particles 33a having a diameter of 200 nm to 500 nm. desirable. More preferably, it is particularly desirable that protruding particles 33a having a diameter of 200 nm to 500 nm and fine particles 33b of 50 nm to 100 nm are mixed on the outermost surface of the conductive member (see Example I-8). However, in this embodiment, as shown in FIG. 4C, the protruding particles 33a having a diameter of 200 nm to 500 nm may not be provided on the outermost surface of the conductive member. More specifically, on the outermost surface of the conductive member, there are no protruding particles 33a having a diameter of 200 nm to 500 nm, and the conductive carbon layer 33 is composed of only fine particles 33b of 50 nm to 100 nm. Also good. Even in such a configuration, if the strength ratio R of the conductive carbon layer 33 is 1.3 or more, the intended object of the present invention can be achieved (see Example I-9).
　図４Ｂに示す形態では、導電性炭素層３３と金属基材３１との間に中間層３２を設け、その中間層３２の結晶構造を制御し、柱状結晶の柱径を導電性炭素層３３との界面まで太くすることで、その上に形成される導電性炭素層３３における隙間や欠陥を低減することができる。そして、最表面において２００ｎｍ～５００ｎｍ、好ましくは３００ｎｍ～５００ｎｍ、より好ましくは４００ｎｍ～５００ｎｍの径を持つ突起状粒子３３ａが存在する場合、導電部材の最表面の隙間の数が減少し、水の侵入を抑制することができる。また、突起状粒子３３ａ以外の周辺部（いわゆる凹凸変化量の小さい平坦部）に微小粒子３３ｂが存在している場合、導電性炭素層３３における隙間や欠陥を低減する上で特に効果的である。こうした構造により、金属基材３１への中間層３２の防食機能を高めつつ、導電性炭素層３３での防食機能を向上することができ、被覆率を落とさずに薄膜化することが可能となる。とりわけ、金属基材３１の防食効果を高めることができ、アルミニウムのような腐食しやすい金属の場合でも金属基材３１として適用できる。 In the form shown in FIG. 4B, an intermediate layer 32 is provided between the conductive carbon layer 33 and the metal substrate 31, the crystal structure of the intermediate layer 32 is controlled, and the column diameter of the columnar crystal is set to the conductive carbon layer 33. By thickening the interface, gaps and defects in the conductive carbon layer 33 formed thereon can be reduced. In the case where the protruding particles 33a having a diameter of 200 nm to 500 nm, preferably 300 nm to 500 nm, more preferably 400 nm to 500 nm are present on the outermost surface, the number of gaps on the outermost surface of the conductive member is reduced and water enters. Can be suppressed. Further, when the fine particles 33b are present in the peripheral portion other than the protruding particles 33a (a flat portion having a small unevenness change amount), it is particularly effective in reducing gaps and defects in the conductive carbon layer 33. . With such a structure, it is possible to improve the anticorrosion function of the conductive carbon layer 33 while enhancing the anticorrosion function of the intermediate layer 32 to the metal substrate 31, and to reduce the thickness without reducing the coverage. . In particular, the anticorrosion effect of the metal substrate 31 can be enhanced, and even a metal that is easily corroded such as aluminum can be applied as the metal substrate 31.
　なお、ここでいう、導電部材（導電性炭素層３３）の最表面の突起状粒子３３ａの径は、粒度分布の範囲をいう。導電部材の最表面の突起状粒子３３ａの径の測定方法は、走査型電子顕微鏡（ＳＥＭ）や透過型電子顕微鏡（ＴＥＭ）などの観察手段を用い、数～数十視野中に観察される粒子の直径の平均値として算出される。同様に、導電部材の最表面の微小粒子３３ｂの大きさ（径）も、粒度分布の範囲をいう。導電部材の最表面の微小粒子３３ｂの大きさの測定も、突起状粒子３３ａと同様に行うことができる。特に突起状粒子３３ａの粒子径は、試料表面のＳＥＭによる観察結果から、コントラストの薄い（白い）粒子の最大長を測定することにより、求めることができる。 In addition, the diameter of the protruding particle 33a on the outermost surface of the conductive member (conductive carbon layer 33) here refers to the range of particle size distribution. The diameter of the protruding particle 33a on the outermost surface of the conductive member is measured by using observation means such as a scanning electron microscope (SEM) or a transmission electron microscope (TEM). It is calculated as an average value of the diameters. Similarly, the size (diameter) of the fine particles 33b on the outermost surface of the conductive member also refers to the range of the particle size distribution. The size of the fine particles 33b on the outermost surface of the conductive member can also be measured in the same manner as the protruding particles 33a. In particular, the particle diameter of the protruding particles 33a can be determined by measuring the maximum length of thin (white) particles having a low contrast from the observation result of the sample surface by SEM.
　導電部材の最表面において、突起状粒子３３ａが１００μｍ２当たり、少なくとも３０個以上、好ましくは３０～１００個、より好ましくは５０～８０個の範囲内で存在しているのが望ましい。この場合、中間層３２中の隙間が減少していることから、表面処理内部における酸化皮膜の形成を抑制することができ、接触抵抗の増加を抑えられる。なお、前記突起状粒子３３ａが１００μｍ２当たりに３０個未満の場合、中間層３２の柱状結晶径の発達が減少していることから、導電部材の最表面における柱状結晶同士の間の隙間数が多くなり、接触抵抗の増加を招く恐れがある。 On the outermost surface of the conductive member, it is desirable that the protruding particles 33a be present in the range of at least 30 or more, preferably 30 to 100, more preferably 50 to 80 per 100 μm 2 . In this case, since the gap in the intermediate layer 32 is reduced, formation of an oxide film inside the surface treatment can be suppressed, and an increase in contact resistance can be suppressed. When the number of the projecting particles 33a is less than 30 per 100 μm 2 , since the development of the columnar crystal diameter of the intermediate layer 32 is reduced, the number of gaps between the columnar crystals on the outermost surface of the conductive member is reduced. This may increase the contact resistance.
　なお、前記突起状粒子３３ａの１００μｍ２当たりの個数が３０個未満であっても、本実施形態の効果を損なわない範囲内であれば、１個以上のものであっても本発明に含まれる。つまり、本実施形態では、中間層３２の構成とは別に、導電性炭素層３３に含まれる炭素の結晶構造を制御することで、導電性炭素層３３の一方の面から他方の面への導電パスが確保されるため、優れた導電性を十分に確保しつつ、耐食性がより一層向上した導電部材が提供される（図４Ｃ、図１５Ａ、図１６Ａ、図１７Ａ、図１８Ａ、実施例I－９参照）。 In addition, even if the number of the protruding particles 33a per 100 μm 2 is less than 30, even if it is within the range not impairing the effect of the present embodiment, it is included in the present invention. . In other words, in this embodiment, by controlling the crystal structure of carbon contained in the conductive carbon layer 33 separately from the configuration of the intermediate layer 32, the conductivity from one surface of the conductive carbon layer 33 to the other surface is controlled. Since the path is secured, a conductive member having sufficiently improved corrosion resistance while sufficiently securing excellent conductivity is provided (FIGS. 4C, 15A, 16A, 17A, 18A, Example I- 9).
　また、最表面の突起状粒子３３ａ同士の頂点間の距離は、１μｍ以内であることが望ましい（図４Ｂ参照）。かかる構成により面内に均一に突起状粒子３３ａが形成されるため、金属基材３１の防錆能が向上する。その結果、金属基材３１への中間層３２の防食機能を高めつつ、導電性炭素層３３での防食機能を向上することができ、被覆率を落とさずに薄膜化することが可能となる。 Further, the distance between the vertices of the outermost protruding particles 33a is preferably within 1 μm (see FIG. 4B). With this configuration, the protruding particles 33a are uniformly formed in the surface, so that the rust preventive ability of the metal base 31 is improved. As a result, it is possible to improve the anticorrosion function of the conductive carbon layer 33 while enhancing the anticorrosion function of the intermediate layer 32 to the metal substrate 31, and it is possible to reduce the thickness without reducing the coverage.
　導電部材の最表面において、突起状粒子３３ａの高さＨが、その周辺部に対して、１００ｎｍ～５００ｎｍ、好ましくは２００ｎｍ～５００ｎｍ、より好ましくは３００ｎｍ～４００ｎｍであることが望ましい（図４Ｂ参照）。これは、突起状粒子３３ａ高さＨが上記範囲内の場合、中間層３２の柱状結晶が成長し、中間層の柱径Ｗが太くなっていることから、中間層中の隙間が更に減少し、金属基材３１の防食機能を一層向上することができる。また、導電部材の最表面に突起状粒子３３ａが存在する突起状形状を有している場合、比表面積が向上する。そして、導電性炭素層３３の最表面が親水性を示す場合、比表面積の向上により親水度が増すため、表面のぬれ性が向上する効果もある。この点をより詳しく説明すれば、試料表面上の水滴の静的接触角が９０度以下で、さらに親水性表面が微細な凹凸形状している場合、親水度が向上することが知られている。表面の親水性が向上すると、排水性が向上するため、フラッディング現象によるガス拡散性低下を抑制することができる。なお、最表面の突起状粒子３３ａのその周辺部に対する高さＨは、下記測定方法による平均値を用いるものとする。さらに、本明細書で用いる導電性炭素層に関する用語や測定法を以下に説明する。 On the outermost surface of the conductive member, it is desirable that the height H of the protruding particles 33a is 100 nm to 500 nm, preferably 200 nm to 500 nm, more preferably 300 nm to 400 nm with respect to the peripheral portion (see FIG. 4B). . This is because, when the height H of the protruding particles 33a is within the above range, the columnar crystal of the intermediate layer 32 grows and the column diameter W of the intermediate layer is increased, so that the gap in the intermediate layer is further reduced. Further, the anticorrosion function of the metal substrate 31 can be further improved. In addition, when the conductive member has a protruding shape in which the protruding particles 33a are present on the outermost surface, the specific surface area is improved. And when the outermost surface of the electroconductive carbon layer 33 shows hydrophilicity, since hydrophilicity increases by the improvement of a specific surface area, there also exists an effect which the wettability of a surface improves. To explain this point in more detail, it is known that when the static contact angle of water droplets on the sample surface is 90 degrees or less and the hydrophilic surface has a fine irregular shape, the hydrophilicity is improved. . When the hydrophilicity of the surface is improved, the drainage property is improved, so that a decrease in gas diffusibility due to a flooding phenomenon can be suppressed. In addition, the average value by the following measuring method shall be used for the height H with respect to the peripheral part of the protrusion-like particle | grains 33a of the outermost surface. Further, terms and measurement methods related to the conductive carbon layer used in this specification will be described below.
　（ａ）突起状粒子３３ａとは、導電性炭素層の一部を構成する粒子であり、さらに中間層の突起に沿って突出しているものをいう。また、微小粒子３３ｂとは、導電性炭素層の一部を構成する粒子であるが、上記突起状粒子と比較して突出していないものをいう。なお、突起状粒子３３ａ及び微小粒子３３ｂの径の測定方法については、ＳＥＭによる表面観察から確認されるコントラストから１つの粒子を拾い、その粒子の平均径により求めることができる。 (A) The protruding particles 33a are particles that constitute a part of the conductive carbon layer, and further protrude along the protrusions of the intermediate layer. The fine particles 33b are particles that constitute a part of the conductive carbon layer but do not protrude as compared with the protruding particles. In addition, about the measuring method of the diameter of the protrusion-shaped particle | grains 33a and the microparticles | fine-particles 33b, one particle | grain can be picked up from the contrast confirmed from the surface observation by SEM, and it can obtain | require by the average diameter of the particle | grains.
　（ｂ）突起状粒子３３ａの高さＨ（Ｈ１，Ｈ２，Ｈ３）とは、突起状粒子３３ａの周りに存在する微小粒子３３ｂの表面から突起状粒子３３ａの先端までの高さをいう。なお、突起状粒子３３ａの高さは、ＴＥＭによる断面観察より求めることができる。 (B) The height H (H 1 , H 2 , H 3 ) of the protruding particle 33a is the height from the surface of the microparticle 33b existing around the protruding particle 33a to the tip of the protruding particle 33a. Say. Note that the height of the protruding particles 33a can be obtained by cross-sectional observation with a TEM.
　（ｃ）１００μｍ２当たりの２００～５００ｎｍの径を持つ突起状粒子３３ａの個数の測定方法については、次のように行う。まず、ＳＥＭによる表面観察により、コントラストとして白く確認される粒子状のものを突起状粒子として捉える。次に、１００μｍ２中に存在する、上記粒子径を有する粒子の個数を測定する。
　（ｄ）５０～１００ｎｍの径の微小粒子３３ｂの測定方法については、ＳＥＭによる表面観察により、上記粒径を持つ粒子を測定することができる。 (C) The method for measuring the number of protruding particles 33a having a diameter of 200 to 500 nm per 100 μm 2 is performed as follows. First, the particle-like thing confirmed as white as contrast by surface observation by SEM is caught as a protruding particle. Next, the number of particles having the above particle diameter present in 100 μm 2 is measured.
(D) Regarding the method for measuring the microparticles 33b having a diameter of 50 to 100 nm, the particles having the above particle diameter can be measured by surface observation with an SEM.
　なお、本実施形態では導電性炭素層３３は、実質的に多結晶グラファイトのみから構成されても良いし、多結晶グラファイトのみから構成されても良いが、導電性炭素層３３は多結晶グラファイト以外の材料をも含むことができる。当該多結晶グラファイト以外の炭素材料としては、グラファイトブロック（高結晶性グラファイト）、カーボンブラック、フラーレン、カーボンナノチューブ、カーボンナノファイバ、カーボンナノホーン、カーボンフィブリルなどが挙げられる。また、カーボンブラックの具体例として、ケッチェンブラック、アセチレンブラック、チャンネルブラック、ランプブラック、オイルファーネスブラックもしくはサーマルブラックなどが挙げられる。なお、カーボンブラックは、グラファイト化処理が施されていても良い。また、これらの炭素材料を、ポリエステル系樹脂、アラミド系樹脂、ポリプロピレン系樹脂のような樹脂と複合化させて用いても良い。また、導電性炭素層３３に含まれる炭素材料以外の材料としては、金（Ａｕ）、銀（Ａｇ）、白金（Ｐｔ）、ルテニウム（Ｒｕ）、パラジウム（Ｐｄ）、ロジウム（Ｒｈ）、インジウム（Ｉｎ）等の貴金属；ポリテトラフルオロエチレン（ＰＴＦＥ）等の撥水性物質；導電性酸化物などが挙げられる。多結晶グラファイト以外の材料は、一種のみが用いられても良いし、二種以上が併用されても良い。 In the present embodiment, the conductive carbon layer 33 may be substantially composed only of polycrystalline graphite or may be composed only of polycrystalline graphite, but the conductive carbon layer 33 is other than polycrystalline graphite. Other materials may also be included. Examples of the carbon material other than the polycrystalline graphite include graphite block (highly crystalline graphite), carbon black, fullerene, carbon nanotube, carbon nanofiber, carbon nanohorn, and carbon fibril. Specific examples of carbon black include ketjen black, acetylene black, channel black, lamp black, oil furnace black, or thermal black. Carbon black may be subjected to a graphitization treatment. These carbon materials may be used in combination with a resin such as a polyester resin, an aramid resin, or a polypropylene resin. In addition, as a material other than the carbon material included in the conductive carbon layer 33, gold (Au), silver (Ag), platinum (Pt), ruthenium (Ru), palladium (Pd), rhodium (Rh), indium ( A noble metal such as In); a water repellent material such as polytetrafluoroethylene (PTFE); and a conductive oxide. As for materials other than polycrystalline graphite, only 1 type may be used and 2 or more types may be used together.
　当該多結晶グラファイト以外の炭素材料が粒子状の場合の平均粒子径は、導電性炭素層の厚みを抑える観点から、好ましくは２ｎｍ～１００ｎｍ、より好ましくは５ｎｍ～２０ｎｍである。なお、ここでの「粒子径」とは、粒子の輪郭線上の任意の２点間の距離のうち、最大の距離を意味するものとする。また「平均粒子径」の値としては、特に言及のない限り、ＳＥＭやＴＥＭなどの観察手段を用い、数～数十視野中に観察される粒子の粒子径の平均値として算出される値を採用するものとする。 The average particle size when the carbon material other than the polycrystalline graphite is in the form of particles is preferably 2 nm to 100 nm, more preferably 5 nm to 20 nm, from the viewpoint of suppressing the thickness of the conductive carbon layer. Here, the “particle diameter” means the maximum distance among the distances between any two points on the particle outline. The value of “average particle size” is a value calculated as an average value of the particle size of particles observed in several to several tens of fields using an observation means such as SEM or TEM unless otherwise specified. Shall be adopted.
　当該多結晶グラファイト以外の炭素材料がカーボンナノチューブなどの繊維状の場合の直径は、好ましくは０．４ｎｍ～１００ｎｍ、より好ましくは１ｎｍ～２０ｎｍである。一方、前記繊維状の場合の長さは、５ｎｍ～２００ｎｍ、より好ましくは１０ｎｍ～１００ｎｍである。そして、前記繊維状の場合のアスペクト比は、１～５００、より好ましくは２～１００である。上記した範囲内にある場合、導電性炭素層の厚さを好適に抑えることができる。 When the carbon material other than the polycrystalline graphite is in the form of a fiber such as a carbon nanotube, the diameter is preferably 0.4 nm to 100 nm, more preferably 1 nm to 20 nm. On the other hand, the length in the case of the fibrous form is 5 nm to 200 nm, more preferably 10 nm to 100 nm. The aspect ratio in the case of the fibrous form is 1 to 500, more preferably 2 to 100. When it exists in the above-mentioned range, the thickness of a conductive carbon layer can be restrained suitably.
　突起状粒子３３ａを除く導電性炭素層３３の平均厚さは、好ましくは１ｎｍ～１０００ｎｍであり、より好ましくは２ｎｍ～５００ｎｍであり、さらに好ましくは５ｎｍ～２００ｎｍである。導電性炭素層３３の厚さがこのような範囲内の値であれば、ガス拡散基体と金属セパレータ５との間に十分な導電性を確保することができる。また、金属基材３１に対して高い耐食機能を持たせることができる。なお、本実施形態では、導電性炭素層３３は、図３に示すように導電部材（金属セパレータ５）の一方の表面にのみ存在させても良いが、好ましくは図２、図４Ａなどに示すように、導電部材の両表面に導電性炭素層３３が存在するのが望ましい。これは、導電部材の両表面において、中間層３２を介して金属基材３１と導電性炭素層３３との密着性を確保しつつ、金属基材３１の防食効果をより一層維持できるためである。 The average thickness of the conductive carbon layer 33 excluding the protruding particles 33a is preferably 1 nm to 1000 nm, more preferably 2 nm to 500 nm, and further preferably 5 nm to 200 nm. When the thickness of the conductive carbon layer 33 is a value within such a range, sufficient conductivity can be ensured between the gas diffusion base and the metal separator 5. In addition, the metal base 31 can have a high corrosion resistance function. In the present embodiment, the conductive carbon layer 33 may be present only on one surface of the conductive member (metal separator 5) as shown in FIG. 3, but preferably shown in FIG. 2, FIG. 4A, and the like. Thus, it is desirable that the conductive carbon layers 33 exist on both surfaces of the conductive member. This is because the anticorrosion effect of the metal substrate 31 can be further maintained while securing the adhesion between the metal substrate 31 and the conductive carbon layer 33 via the intermediate layer 32 on both surfaces of the conductive member. .
　さらに、導電性炭素層３３のラマン散乱分光分析について、ラマン散乱分光分析の回転異方性測定により測定された平均ピークが、２回対称パターンを示すことが好ましい。以下、回転異方性測定の測定原理について、簡単に説明する。 Furthermore, for the Raman scattering spectroscopic analysis of the conductive carbon layer 33, it is preferable that the average peak measured by the rotational anisotropy measurement of the Raman scattering spectroscopic analysis shows a two-fold symmetry pattern. Hereinafter, the measurement principle of rotational anisotropy measurement will be briefly described.
　ラマン散乱分光分析の回転異方性測定は、測定サンプルを水平方向に３６０度回転させながら、ラマン散乱分光測定を実施することにより行われる。具体的には、測定サンプルの表面に対してレーザー光を照射し、通常のラマンスペクトルを測定する。次いで、測定サンプルを１０°回転させて、同様にラマンスペクトルを測定する。この操作を、測定サンプルが３６０°回転するまで行う。そして、それぞれの角度で得られたピーク強度の平均値を算出し、測定されたピーク強度のうち最も弱いものを中心Ｏとして、１周３６０°の極座標表示とすることにより、平均ピークが得られる。そして、例えば、グラフェン面がサンプルの面方向と平行となるように、グラファイト層がサンプル表面に存在する場合には、図６Ａに示すような３回対称パターンが見られる。一方、グラフェン面がサンプルの面方向と垂直となるように、グラファイト層がサンプル表面に存在する場合には、図６Ｂに示すような２回対称パターンが見られる。なお、明確な結晶構造が存在しない非晶質状の炭素層がサンプル表面に存在する場合には、図６Ｃに示すような対称性を示さないパターンが見られる。したがって、回転異方性測定により測定された平均ピークガ２回対称パターンを示すということは、導電性炭素層３３を構成するグラフェン面の面方向が、導電性炭素層３３の積層方向とほぼ一致していることを意味する。このような形態によれば、導電性炭素層３３における導電性が最短のパスによって確保されることとなるため、好ましい。 Rotational anisotropy measurement of Raman scattering spectroscopic analysis is performed by performing Raman scattering spectroscopic measurement while rotating the measurement sample 360 degrees in the horizontal direction. Specifically, the surface of the measurement sample is irradiated with laser light, and a normal Raman spectrum is measured. Next, the measurement sample is rotated by 10 °, and the Raman spectrum is measured in the same manner. This operation is performed until the measurement sample rotates 360 °. And the average peak is obtained by calculating the average value of the peak intensities obtained at the respective angles, and displaying the weakest of the measured peak intensities as the center O and displaying the polar coordinates at 360 ° per revolution. . For example, when the graphite layer is present on the sample surface so that the graphene surface is parallel to the surface direction of the sample, a three-fold symmetry pattern as shown in FIG. 6A can be seen. On the other hand, when the graphite layer is present on the sample surface so that the graphene surface is perpendicular to the surface direction of the sample, a two-fold symmetry pattern as shown in FIG. 6B can be seen. When an amorphous carbon layer having no clear crystal structure is present on the sample surface, a pattern not showing symmetry as shown in FIG. 6C can be seen. Therefore, the fact that the average peak ga symmetric pattern measured by rotational anisotropy measurement shows a plane direction of the graphene surface constituting the conductive carbon layer 33 substantially coincides with the stacking direction of the conductive carbon layer 33. Means that According to such a form, the conductivity in the conductive carbon layer 33 is ensured by the shortest path, which is preferable.
　ここで、上述した当該回転異方性測定を行った結果を図７Ａ及び図７Ｂに示す。図７Ａは、導電部材Ｂを測定サンプルとして用い、当該サンプルの回転角をそれぞれ０°、６０°、及び１８０°としたときのラマンスペクトルを示す。また、図７Ｂは、上述した手法により得られた、導電部材Ｂについての回転異方性測定の平均ピークを示す。図７Ｂに示すように、導電部材Ｂの回転異方性測定においては、０°及び１８０°の位置にピークが見られた。これは、図６Ｂに示す２回対称パターンに相当する。なお、本明細書において、「２回対称パターンを示す」とは、図６Ｂ及び図７Ｂに示すように、平均ピークにおいて、ピーク強度が最小である点を基準として１８０°対向する２つのピークが存在することを意味する。３回対称パターンで見られるピーク強度と２回対称パターンで見られるピーク強度とは原理的には同程度の値を示すとされているため、このような定義が可能となる。 Here, the results of the rotational anisotropy measurement described above are shown in FIGS. 7A and 7B. FIG. 7A shows a Raman spectrum when the conductive member B is used as a measurement sample and the rotation angles of the sample are 0 °, 60 °, and 180 °, respectively. FIG. 7B shows an average peak of rotational anisotropy measurement for the conductive member B obtained by the above-described method. As shown in FIG. 7B, in the measurement of rotational anisotropy of the conductive member B, peaks were observed at 0 ° and 180 ° positions. This corresponds to the two-fold symmetry pattern shown in FIG. 6B. In this specification, “showing a two-fold symmetry pattern” means that, as shown in FIG. 6B and FIG. 7B, two peaks facing each other by 180 ° with respect to a point where the peak intensity is the minimum in the average peak. It means to exist. Such definition is possible because the peak intensity seen in the three-fold symmetry pattern and the peak intensity seen in the two-fold symmetry pattern are theoretically equivalent.
　本実施形態では、導電性炭素層３３のビッカース硬度が規定される。「ビッカース硬度（Ｈｖ）」とは、物質の硬さを規定する値であり、物質に固有の値である。本明細書において、ビッカース硬度は、ナノインデンテーション法により測定された値を意味する。ナノインデンテーション法とは、サンプル表面に対して超微小な荷重でダイヤモンド圧子を連続的に負荷及び除荷し、得られた荷重－変位曲線から硬さを測定するという手法であり、Ｈｖが大きいほどその物質は硬いことを意味する。好ましい実施形態において、具体的には、導電性炭素層３３のビッカース硬度は、好ましくは１５００Ｈｖ以下であり、より好ましくは１２００Ｈｖ以下であり、さらに好ましくは１０００Ｈｖ以下であり、特に好ましくは８００Ｈｖ以下である。ビッカース硬度がこのような範囲内の値であれば、導電性を有しないｓｐ３炭素の過剰な混入が抑制され、導電性炭素層３３の導電性の低下を防止することができる。一方、ビッカース硬度の下限値について特に制限はないが、ビッカース硬度が５０Ｈｖ以上であれば、導電性炭素層３３の硬度が十分に確保される。その結果、外部からの接触や摩擦等の衝撃にも耐えることができ、下地である金属基材３１との密着性にも優れた導電部材（セパレータ５）を提供することができる。更には本実施形態のように中間層３２を設ける態様では、導電性炭素層３３と該中間層３２、更には金属基材３１より一層強固な密着性にも優れた導電部材を提供することができる。このような観点から、導電性炭素層３３のビッカース硬度は、より好ましくは８０Ｈｖ以上であり、さらに好ましくは１００Ｈｖ以上であり、特に好ましくは２００Ｈｖ以上である。 In the present embodiment, the Vickers hardness of the conductive carbon layer 33 is defined. “Vickers hardness (Hv)” is a value that defines the hardness of a substance, and is a value inherent to the substance. In this specification, the Vickers hardness means a value measured by a nanoindentation method. The nanoindentation method is a method in which the diamond indenter is continuously loaded and unloaded with a very small load on the sample surface, and the hardness is measured from the obtained load-displacement curve. Larger means that the substance is harder. In a preferred embodiment, specifically, the Vickers hardness of the conductive carbon layer 33 is preferably 1500 Hv or less, more preferably 1200 Hv or less, further preferably 1000 Hv or less, and particularly preferably 800 Hv or less. . When the Vickers hardness is a value within such a range, excessive mixing of sp 3 carbon having no conductivity is suppressed, and a decrease in the conductivity of the conductive carbon layer 33 can be prevented. On the other hand, the lower limit value of the Vickers hardness is not particularly limited, but if the Vickers hardness is 50 Hv or more, the hardness of the conductive carbon layer 33 is sufficiently ensured. As a result, it is possible to provide a conductive member (separator 5) that can withstand impacts such as external contact and friction, and has excellent adhesion to the metal substrate 31 as a base. Furthermore, in the embodiment in which the intermediate layer 32 is provided as in the present embodiment, it is possible to provide a conductive member that is more excellent in adhesion than the conductive carbon layer 33 and the intermediate layer 32 and further the metal base 31. it can. From such a viewpoint, the Vickers hardness of the conductive carbon layer 33 is more preferably 80 Hv or more, further preferably 100 Hv or more, and particularly preferably 200 Hv or more.
　ここで、導電部材の金属基材３１としてＳＵＳ３１６Ｌを準備する。この表面にＣｒからなる中間層３２（厚さ０．２μｍ）及び導電性炭素層３３（厚さ０．２μｍ）をスパッタリング法によって順次形成した。ここでの中間層３２には、該中間層３２の断面における柱状結晶の柱の太さの平均値が２００ｎｍ～５００ｎｍであり、当該太さを持つ柱状結晶が該中間層３２全体のうち、導電性炭素層３３側に該中間層膜厚全体の６０％存在している。また、導電性炭素層３３には、最表面において、２００ｎｍ～５００ｎｍの径（粒度分布）を持つ突起状粒子３３ａと、５０ｎｍ～１００ｎｍの微小粒子３３ｂが混在しており、前記突起状粒子３３ａが１００μｍ２当たりに、平均６０個存在している。この際、バイアス電圧及び成膜方式を制御することにより、中間層３２の結晶構造を制御し、所期の柱径や個数を持つ柱状結晶径を作成した後、導電性炭素層３３のビッカース硬度を変化させた。これにより得られた導電部材における導電性炭素層３３のビッカース硬度とｓｐ３比の値との関係を図８に示す。なお、図８では、ダイヤモンドはｓｐ３比＝１００％であり、Ｈｖ１００００となる。図８に示す結果から、導電性炭素層３３のビッカース硬度が１５００Ｈｖ以下であると、ｓｐ３比の値が大きく低下することがわかる。また、ｓｐ３比の値が低下することで、導電部材の接触抵抗の値もこれに伴って低下することが推測される。 Here, SUS316L is prepared as the metal base 31 of the conductive member. On this surface, an intermediate layer 32 (thickness 0.2 μm) made of Cr and a conductive carbon layer 33 (thickness 0.2 μm) were sequentially formed by sputtering. In this intermediate layer 32, the average value of the columnar crystal column thickness in the cross section of the intermediate layer 32 is 200 nm to 500 nm, and the columnar crystal having this thickness is electrically conductive in the entire intermediate layer 32. 60% of the total thickness of the intermediate layer is present on the carbonaceous carbon layer 33 side. In addition, the conductive carbon layer 33 has a mixture of protruding particles 33a having a diameter (particle size distribution) of 200 nm to 500 nm and fine particles 33b of 50 nm to 100 nm on the outermost surface, and the protruding particles 33a are mixed. There are 60 on average per 100 μm 2 . At this time, by controlling the bias voltage and the film formation method, the crystal structure of the intermediate layer 32 is controlled to create a columnar crystal diameter having a desired column diameter and number, and then the Vickers hardness of the conductive carbon layer 33. Changed. FIG. 8 shows the relationship between the Vickers hardness of the conductive carbon layer 33 and the value of the sp 3 ratio in the conductive member thus obtained. In FIG. 8, diamond has an sp 3 ratio = 100% and becomes Hv10000. From the results shown in FIG. 8, it can be seen that when the Vickers hardness of the conductive carbon layer 33 is 1500 Hv or less, the value of the sp 3 ratio is greatly reduced. Further, it is presumed that the value of the contact resistance of the conductive member also decreases as the value of the sp 3 ratio decreases.
　さらに、本実施形態では、導電性炭素層３３に含まれる水素原子の量も考慮することが好ましい。すなわち、導電性炭素層３３に水素原子が含まれる場合、当該水素原子は炭素原子と結合する。そうすると、水素原子が結合した炭素原子の混成軌道はｓｐ２からｓｐ３へと変化して導電性を喪失し、導電性炭素層３３の導電性が低下することとなる。また、多結晶グラファイトにおけるＣ－Ｈ結合が増加すると、結合の連続性が失われ、導電性炭素層３３の硬度が低下し、最終的には導電部材の機械的強度や耐食性が低下してしまう。このような観点から、導電性炭素層３３における水素原子の含有量は、導電性炭素層３３を構成する全原子に対して、好ましくは３０原子％以下であり、より好ましくは２０原子％以下であり、さらに好ましくは１０原子％以下である。ここで、導電性炭素層３３における水素原子の含有量の値としては、弾性反跳散乱分析法（ＥＲＤＡ）により得られる値を採用するものとする。この方法では、測定サンプルを傾け、ヘリウムイオンビームを浅く入射することによって、前方に弾き出された元素を検出する。水素原子の原子核は、入射されるヘリウムイオンよりも軽いため、水素原子が存在するとその原子核は前方に弾き出される。このような散乱は弾性散乱であることから、弾き出された原子のエネルギースペクトルはその原子核の質量を反映することになる。したがって、弾き出された水素原子の原子核の数を固体検出器によって測定することにより、測定サンプルにおける水素原子の含有量が測定される。 Further, in the present embodiment, it is preferable to consider the amount of hydrogen atoms contained in the conductive carbon layer 33. That is, when the conductive carbon layer 33 includes a hydrogen atom, the hydrogen atom is bonded to the carbon atom. Then, the hybrid orbital of the carbon atom to which the hydrogen atom is bonded is changed from sp 2 to sp 3 and the conductivity is lost, and the conductivity of the conductive carbon layer 33 is lowered. Further, when the C—H bond in the polycrystalline graphite is increased, the continuity of the bond is lost, the hardness of the conductive carbon layer 33 is lowered, and finally the mechanical strength and corrosion resistance of the conductive member are lowered. . From such a viewpoint, the content of hydrogen atoms in the conductive carbon layer 33 is preferably 30 atomic percent or less, more preferably 20 atomic percent or less, with respect to all atoms constituting the conductive carbon layer 33. More preferably, it is 10 atomic% or less. Here, as the value of the hydrogen atom content in the conductive carbon layer 33, a value obtained by elastic recoil scattering analysis (ERDA) is adopted. In this method, a measurement sample is tilted, and a helium ion beam is incident shallowly, thereby detecting an element ejected forward. Since the nucleus of a hydrogen atom is lighter than the incident helium ion, if a hydrogen atom is present, the nucleus is ejected forward. Since such scattering is elastic scattering, the energy spectrum of the ejected atom reflects the mass of the nucleus. Therefore, the content of hydrogen atoms in the measurement sample is measured by measuring the number of nuclei of the ejected hydrogen atoms with a solid detector.
　ここで、図９は、上述したＲ値が１．３以上であるものの、水素原子の含有量が異なる導電性炭素層３３を有するいくつかの導電部材について、接触抵抗を測定した結果を示すグラフである。図９に示すように、導電性炭素層３３における水素原子の含有量が３０原子％以下であると、導電部材の接触抵抗の値は顕著に低下する。なお、図９に示す実験において、導電部材の金属基材３１としてはＳＵＳ３１６Ｌを用いた。この表面上にＣｒからなる中間層３２（厚さ０．２μｍ）及び導電性炭素層３３（厚さ０．２μｍ）をスパッタリング法によって順次形成することにより作製した。この際、成膜方式や炭化水素ガス量を制御することにより、導電性炭素層における水素原子の含有量を変化させた。 Here, FIG. 9 is a graph showing the results of measuring the contact resistance of several conductive members having the conductive carbon layer 33 having the above-described R value of 1.3 or more but having different hydrogen atom contents. It is. As shown in FIG. 9, when the content of hydrogen atoms in the conductive carbon layer 33 is 30 atomic% or less, the value of the contact resistance of the conductive member is significantly reduced. In the experiment shown in FIG. 9, SUS316L was used as the metal base 31 of the conductive member. An intermediate layer 32 (thickness 0.2 μm) made of Cr and a conductive carbon layer 33 (thickness 0.2 μm) were sequentially formed on the surface by sputtering. At this time, the hydrogen atom content in the conductive carbon layer was changed by controlling the film formation method and the amount of hydrocarbon gas.
　本実施形態においては、中間層３２を介して金属基材３１のすべてが、導電性炭素層３３により被覆されている。換言すれば、本実施形態では、導電性炭素層３３により金属基材３１が被覆された面積の割合（被覆率）は１００％である。ただし、このような形態のみには限定されず、被覆率は１００％未満であっても良い。導電性炭素層３３による金属基材３１の被覆率は、好ましくは５０％以上であり、より好ましくは８０％以上であり、さらに好ましくは９０％以上であり、最も好ましくは１００％である。このような構成とすることにより、導電性炭素層３３により被覆されていない、金属基材３１の露出部への酸化皮膜の形成に伴う導電性・耐食性の低下が効果的に抑制される。なお、本実施形態のように、後述する中間層３２が金属基材３１と導電性炭素層３３との間に介在する場合、上記被覆率は、導電部材（金属セパレータ５）を積層方向から見た場合に導電性炭素層３３と重複する金属基材３１の面積の割合を意味するものとする。 In the present embodiment, the entire metal base 31 is covered with the conductive carbon layer 33 through the intermediate layer 32. In other words, in this embodiment, the ratio (coverage) of the area where the metal base 31 is covered with the conductive carbon layer 33 is 100%. However, it is not limited only to such a form, A coverage may be less than 100%. The coverage of the metal substrate 31 by the conductive carbon layer 33 is preferably 50% or more, more preferably 80% or more, still more preferably 90% or more, and most preferably 100%. By setting it as such a structure, the fall of electroconductivity and corrosion resistance accompanying formation of the oxide film in the exposed part of the metal base material 31 which is not coat | covered with the electroconductive carbon layer 33 is suppressed effectively. Note that when the intermediate layer 32 described later is interposed between the metal base 31 and the conductive carbon layer 33 as in the present embodiment, the coverage is determined by viewing the conductive member (metal separator 5) from the stacking direction. In this case, the ratio of the area of the metal substrate 31 overlapping with the conductive carbon layer 33 is meant.
　［中間層］
　図２、３に示すように、本実施形態において、金属セパレータ５を構成する導電部材は、中間層３２を有する。この中間層３２は、金属基材３１と導電性炭素層３３との密着性を向上させるという機能や、金属基材３１からのイオンの溶出を防止するという機能を有する。特に、Ｒ値が上述した好ましい範囲の上限値を超える場合に、中間層３２を設けることによる効果は顕著に発現する。ただし、Ｒ値が上述した好ましい範囲に含まれる場合であっても中間層３２が設けられることは当然である。他の観点からは、中間層３２の設置による上述した作用効果は、金属基材３１がアルミニウム又はその合金から構成される場合により一層顕著に発現する。以下、中間層３２の好ましい形態について説明する。まず、本明細書で用いる中間層に関する用語や測定法を以下に説明する。 [Middle layer]
As shown in FIGS. 2 and 3, in this embodiment, the conductive member constituting the metal separator 5 has an intermediate layer 32. The intermediate layer 32 has a function of improving the adhesion between the metal substrate 31 and the conductive carbon layer 33 and a function of preventing elution of ions from the metal substrate 31. In particular, when the R value exceeds the upper limit of the preferable range described above, the effect of providing the intermediate layer 32 is remarkably exhibited. However, it is a matter of course that the intermediate layer 32 is provided even when the R value is included in the preferred range described above. From another point of view, the above-described operation and effect due to the installation of the intermediate layer 32 are more prominently exhibited when the metal substrate 31 is made of aluminum or an alloy thereof. Hereinafter, the preferable form of the intermediate | middle layer 32 is demonstrated. First, terms and measurement methods related to the intermediate layer used in this specification will be described below.
　（ａ）柱状結晶構造は、中間層を構成している結晶が、膜厚方向に柱状に成長している構造をいう。 (A) The columnar crystal structure refers to a structure in which the crystals constituting the intermediate layer grow in a columnar shape in the film thickness direction.
　（ｂ）中間層の断面における柱状結晶の柱の太さＷの平均値の測定方法については、次のように求める。まず、ＴＥＭによる断面観察結果から、金属基材３１に対して垂直方向に成長している柱状結晶について、コントラストによって確認される柱の界面から１本の柱を特定し、その金属基材と平行方向の一方の界面から他方の界面の距離を算出することにより求めることができる。 (B) The method for measuring the average value of the column thickness W of the columnar crystals in the cross section of the intermediate layer is determined as follows. First, from a cross-sectional observation result by TEM, for a columnar crystal growing in a direction perpendicular to the metal substrate 31, one column is specified from the interface of the column confirmed by contrast, and is parallel to the metal substrate. It can be obtained by calculating the distance from one interface in the direction to the other interface.
　（ｃ）該中間層の断面における柱状結晶の柱の太さが２００～５００ｎｍであり、当該太さを持つ柱状結晶が該中間層全体のうち、導電性炭素層側に中間層膜厚全体の何％存在するかについては、次のように求める。図４Ｂに示すように、ＴＥＭによる断面観察結果から、中間層の平均厚さＴ１に対する上記太さを持つ柱状結晶の厚さＴ２の割合（Ｔ２／Ｔ１）として求める。なお、中間層の厚さＴ１は、中間層における突起３２ａの高さＨ４を除いた厚さとする。 (C) The thickness of the columnar crystal column in the cross section of the intermediate layer is 200 to 500 nm, and the columnar crystal having the thickness of the intermediate layer has the entire intermediate layer thickness on the conductive carbon layer side of the entire intermediate layer. The percentage is calculated as follows. As shown in FIG. 4B, the ratio (T 2 / T 1 ) of the thickness T 2 of the columnar crystal having the above thickness with respect to the average thickness T 1 of the intermediate layer is obtained from the cross-sectional observation result by TEM. The thickness T 1 of the intermediate layer, the thickness excluding the height H 4 of the projections 32a in the intermediate layer.
　（ｄ）中間層全体のうち導電性炭素層側とは、中間層の厚さ方向において、導電性炭素層側の５０％の領域をいう。 (D) The conductive carbon layer side in the entire intermediate layer refers to a 50% region on the conductive carbon layer side in the thickness direction of the intermediate layer.
　（ｅ）中間層の膜厚（平均値）の測定方法は、ＳＥＭ又はＴＥＭによる断面観察結果から読み取ることができる。 (E) The measuring method of the film thickness (average value) of the intermediate layer can be read from the cross-sectional observation result by SEM or TEM.
　上述のように、中間層３２は柱状結晶構造を有している。そして、詳細は後述するが、導電部材の最表面に突起状粒子３３ａが存在している中間層３２をスパッタリング法によって形成するのが望ましい。これは、本実施形態によれば、導電性炭素層３３と金属基材３１との間に中間層３２を設け、その中間層３２の柱状結晶構造を制御し、柱状結晶の柱径を導電性炭素層との界面まで太くすることで、中間層３２表面に柱状突起（凸状部）が形成される。その上に導電性炭素層３３を形成することで、中間層３２表面の起伏に沿った導電性炭素層３３の形成される。その結果、前記中間層３２が柱状結晶構造を有し、導電部材の最表面に前記突起状粒子３３ａが存在した構造の導電部材が提供される。かかる導電部材では、最表面に突起状粒子３３ａが存在するように中間層３２の柱状結晶の柱径を太くすることで、中間層３２の柱状結晶間の隙間及びその上に存在する導電性炭素層３３における隙間や欠陥を大幅に低減する。即ち、突起状粒子３３ａは中間層３２の柱状径の発達に起因するものであり、最表層の隙間の数が減少し、水の侵入を抑制する機能を付与することができる。その結果、各界面での酸化を抑制し、優れた導電性を十分に確保しつつ接触抵抗の増加を抑制でき、さらに金属基材３１の防食効果を高めることができる。そして、アルミニウムのような腐食しやすい金属の場合でも、金属セパレータ５の金属基材３１として適用できる。 As described above, the intermediate layer 32 has a columnar crystal structure. And although mentioned later for details, it is desirable to form the intermediate | middle layer 32 in which the protruding particle | grains 33a exist in the outermost surface of an electrically-conductive member by sputtering method. According to this embodiment, the intermediate layer 32 is provided between the conductive carbon layer 33 and the metal substrate 31, the columnar crystal structure of the intermediate layer 32 is controlled, and the column diameter of the columnar crystal is set to be conductive. By thickening the interface with the carbon layer, columnar protrusions (convex portions) are formed on the surface of the intermediate layer 32. By forming the conductive carbon layer 33 thereon, the conductive carbon layer 33 is formed along the undulations on the surface of the intermediate layer 32. As a result, a conductive member having a structure in which the intermediate layer 32 has a columnar crystal structure and the protruding particles 33a exist on the outermost surface of the conductive member is provided. In such a conductive member, by increasing the column diameter of the columnar crystals of the intermediate layer 32 so that the protruding particles 33a exist on the outermost surface, the gap between the columnar crystals of the intermediate layer 32 and the conductive carbon present thereon are formed. The gaps and defects in the layer 33 are greatly reduced. That is, the protruding particles 33a are due to the development of the columnar diameter of the intermediate layer 32, and the number of outermost layer gaps can be reduced to provide a function of suppressing water intrusion. As a result, oxidation at each interface can be suppressed, an increase in contact resistance can be suppressed while sufficiently ensuring excellent conductivity, and the anticorrosion effect of the metal substrate 31 can be further enhanced. Even in the case of a metal that is easily corroded, such as aluminum, it can be applied as the metal substrate 31 of the metal separator 5.
　中間層３２を構成する材料としては、上記の密着性を付与するものが好ましい。例えば、周期律表の第４族の金属（Ｔｉ、Ｚｒ、Ｈｆ）、第５族の金属（Ｖ、Ｎｂ、Ｔａ）、第６族の金属（Ｃｒ、Ｍｏ、Ｗ）、これらの炭化物、窒化物及び炭窒化物などが挙げられる。なかでも好ましくは、クロム（Ｃｒ）、タングステン（Ｗ）、チタン（Ｔｉ）、モリブデン（Ｍｏ）、ニオブ（Ｎｂ）もしくはハフニウム（Ｈｆ）といったイオン溶出の少ない金属、又はこれらの窒化物、炭化物もしくは炭窒化物が用いられる。より好ましくは、ＣｒもしくはＴｉ、又はこれらの炭化物もしくは窒化物が用いられる。特に、ＣｒもしくはＴｉ、又はこれらの炭化物もしくは窒化物が用いる場合、中間層３２の役割として、上側の導電性炭素層３３との密着性確保と、下地の金属基材３１の防食効果がある。特にアルミニウム又はその合金で構成された金属基材３１の場合、界面付近に到達した水分により腐食が進行し、アルミニウムの酸化皮膜の形成が生じる。その結果、金属基材３１全体の膜厚方向の導電性が悪化する。クロム及びチタン（又はこれらの炭化物もしくは窒化物）は不動態皮膜の形成により、露出部が存在していたとしても、それ自体の溶出は殆ど見られない点において特に有用である。なかでも、上述したイオン溶出の少ない金属（特にＣｒもしくはＴｉ）又はその炭化物もしくは窒化物を用いた場合、金属セパレータ５の耐食性を有意に向上させることができる。 As the material constituting the intermediate layer 32, a material that imparts the above-mentioned adhesion is preferable. For example, Group 4 metals (Ti, Zr, Hf), Group 5 metals (V, Nb, Ta), Group 6 metals (Cr, Mo, W), their carbides, nitriding And carbonitrides. Among these, metals with low ion elution such as chromium (Cr), tungsten (W), titanium (Ti), molybdenum (Mo), niobium (Nb) or hafnium (Hf), or their nitrides, carbides or charcoal are preferable. Nitride is used. More preferably, Cr or Ti, or a carbide or nitride thereof is used. In particular, when Cr or Ti, or their carbides or nitrides are used, the role of the intermediate layer 32 is to ensure adhesion with the upper conductive carbon layer 33 and to prevent corrosion of the underlying metal substrate 31. In particular, in the case of the metal substrate 31 made of aluminum or an alloy thereof, corrosion proceeds due to moisture reaching the vicinity of the interface, and an aluminum oxide film is formed. As a result, the conductivity in the film thickness direction of the entire metal base 31 is deteriorated. Chromium and titanium (or their carbides or nitrides) are particularly useful in that, due to the formation of a passive film, even if exposed portions are present, their own elution is hardly observed. Especially, when the metal (especially Cr or Ti) with little ion elution mentioned above or its carbide | carbonized_material or nitride is used, the corrosion resistance of the metal separator 5 can be improved significantly.
　また、中間層３２において、該中間層３２の断面における柱状結晶の柱の太さＷ１，Ｗ２，Ｗ３の平均値が、２００ｎｍ～５００ｎｍ、好ましくは３００ｎｍ～５００ｎｍ、より好ましくは４００ｎｍ～５００ｎｍであることが望ましい。中間層３２の断面における柱状結晶の柱の太さの平均値がかかる範囲の太さの柱状結晶を持つことにより、柱状結晶間の隙間量が減少し、金属基材３１に到達する水分の浸入を抑制することができる。そして、中間層３２を設ける際、中間層３２の結晶構造を制御し、中間層３２の柱状結晶の柱径を導電性炭素層３３との界面まで太くする構成とすることが好ましい。これにより、その上に形成される導電性炭素層３３における隙間や欠陥を格段に低減することができる。導電部材（金属セパレータ５）の最表層における突起状粒子３３ａの粒子径は、柱状結晶の柱径に密接に関連する。そして、柱状結晶の柱径が太くなり、突起状粒子３３ａの粒子径が２００ｎｍ～５００ｎｍになった場合には、導電部材の最表層の隙間の数が減少し、水の侵入を抑制する機能を付与することができる。 Further, in the intermediate layer 32, the average value of the columnar crystal column thicknesses W 1 , W 2 , W 3 in the cross section of the intermediate layer 32 is 200 nm to 500 nm, preferably 300 nm to 500 nm, more preferably 400 nm to 500 nm. It is desirable that By having the columnar crystals having a thickness within such a range that the average column thickness of the columnar crystals in the cross section of the intermediate layer 32 is present, the amount of gaps between the columnar crystals is reduced, and the penetration of moisture reaching the metal substrate 31 Can be suppressed. When providing the intermediate layer 32, it is preferable to control the crystal structure of the intermediate layer 32 so that the column diameter of the columnar crystals of the intermediate layer 32 is increased to the interface with the conductive carbon layer 33. Thereby, the clearance gap and defect in the conductive carbon layer 33 formed on it can be remarkably reduced. The particle diameter of the protruding particles 33a in the outermost layer of the conductive member (metal separator 5) is closely related to the column diameter of the columnar crystals. And when the column diameter of the columnar crystal is increased and the particle diameter of the protruding particles 33a is 200 nm to 500 nm, the number of gaps in the outermost layer of the conductive member is reduced, and the function of suppressing water intrusion is achieved. Can be granted.
　前記中間層３２おいて、その断面における柱状結晶の柱の太さが２００ｎｍ～５００ｎｍであることが好ましい。さらにその太さを持つ柱状結晶に関し、中間層３２膜厚全体の５～９５％がその太さを持つ柱状結晶により構成されており、さらにその太さを持つ柱状結晶が導電性炭素層３３側に存在しているのが望ましい。本実施形態では、中間層３２の最表面における柱状結晶の太さが、出来る限り金属基材３１と中間層３２の界面まで維持されているのが望ましい。しかしながら、金属基材３１上に最初に中間層３２を形成する際、最初から柱状結晶を太くするためには表面に加えるエネルギーが高くする必要がある。そのため、金属基材３１と中間層３２の間に密着不良をおこす場合がある。したがって、図４Ｂに示すように、金属基材３１側の柱状結晶の太さは、導電性炭素層３３側に比べ細い方が好ましい。これにより、金属基材３１、導電性炭素層３３との密着性を確保しつつ、金属基材３１の防食効果をより一層安定に維持できる。ここで、上記中間層３２おいて、その断面における柱状結晶の柱の太さは、２００～５００ｎｍ、好ましくは２００～４００ｎｍ、より好ましくは２００～３００ｎｍである。また、上記太さを持つ柱状結晶が、中間層３２膜厚全体の５～９５％、好ましくは２０～９０％、より好ましくは５０～９０％存在し、さらに上記太さを持つ柱状結晶が導電性炭素層３３側に形成されていることが好ましい。 In the intermediate layer 32, the thickness of the columnar crystal column in the cross section is preferably 200 nm to 500 nm. Further, regarding the columnar crystal having the thickness, 5 to 95% of the total thickness of the intermediate layer 32 is constituted by the columnar crystal having the thickness, and the columnar crystal having the thickness is further on the conductive carbon layer 33 side. It is desirable to exist. In the present embodiment, it is desirable that the thickness of the columnar crystal on the outermost surface of the intermediate layer 32 is maintained up to the interface between the metal base 31 and the intermediate layer 32 as much as possible. However, when the intermediate layer 32 is first formed on the metal substrate 31, it is necessary to increase the energy applied to the surface in order to thicken the columnar crystals from the beginning. Therefore, adhesion failure may occur between the metal base 31 and the intermediate layer 32. Therefore, as shown in FIG. 4B, the thickness of the columnar crystal on the metal substrate 31 side is preferably thinner than that on the conductive carbon layer 33 side. Thereby, the anticorrosion effect of the metal substrate 31 can be maintained more stably while ensuring the adhesion between the metal substrate 31 and the conductive carbon layer 33. Here, in the intermediate layer 32, the columnar crystal column thickness in the cross section is 200 to 500 nm, preferably 200 to 400 nm, and more preferably 200 to 300 nm. Further, the columnar crystals having the above thickness are present in an amount of 5 to 95%, preferably 20 to 90%, more preferably 50 to 90% of the entire thickness of the intermediate layer 32, and the columnar crystals having the above thickness are further conductive. It is preferably formed on the side of the carbonaceous layer 33.
　中間層３２の厚さは、特に制限されない。ただし、金属セパレータ５をより薄膜化することにより、燃料電池スタックのサイズをできるだけ小さくするという観点から、中間層３２の厚さは、好ましくは０．０１μｍ～１０μｍであり、より好ましくは０．０２μｍ～５μｍであり、さらに好ましくは０．０５μｍ～５μｍであり、特に好ましくは０．１μｍ～１μｍである。中間層３２の厚さが０．０１μｍ以上であれば、均一な層が形成され、金属基材３１の耐食性を効果的に向上させることが可能となる。一方、中間層３２の厚さが１０μｍ以下であれば、中間層３２の膜応力の上昇が抑えられ、金属基材３１に対する皮膜追従性の低下やこれに伴う剥離・クラックの発生が防止される。 The thickness of the intermediate layer 32 is not particularly limited. However, from the viewpoint of making the size of the fuel cell stack as small as possible by making the metal separator 5 thinner, the thickness of the intermediate layer 32 is preferably 0.01 μm to 10 μm, more preferably 0.02 μm. Is 5 μm, more preferably 0.05 μm to 5 μm, and particularly preferably 0.1 μm to 1 μm. If the thickness of the intermediate layer 32 is 0.01 μm or more, a uniform layer is formed, and the corrosion resistance of the metal substrate 31 can be effectively improved. On the other hand, if the thickness of the intermediate layer 32 is 10 μm or less, an increase in the film stress of the intermediate layer 32 is suppressed, and a decrease in film followability to the metal substrate 31 and occurrence of peeling / cracking associated therewith are prevented. .
　とりわけ、中間層３２の膜厚が０．０２μｍ～５μｍであるのが望ましい。前記中間層３２が上記範囲内の膜厚を有する場合、以下の構成を有するのが更に望ましい。即ち、中間層３２の導電性炭素層３３側の表面における２００ｎｍ～５００ｎｍの太さを持つ柱状結晶が、導電性炭素層３３から金属基材３１の方向に対して、中間層３２膜厚全体の５％以上で維持されているのが望ましい。また、上記太さの柱状結晶が、導電性炭素層３３から金属基材３１の方向に対して、好ましくは中間層３２膜厚全体の２０～９０％、より好ましくは５０～９０％の範囲で維持されているのが望ましい。 In particular, it is desirable that the thickness of the intermediate layer 32 is 0.02 μm to 5 μm. When the intermediate layer 32 has a film thickness within the above range, it is more desirable to have the following configuration. That is, columnar crystals having a thickness of 200 nm to 500 nm on the surface of the intermediate layer 32 on the side of the conductive carbon layer 33 are the entire thickness of the intermediate layer 32 with respect to the direction from the conductive carbon layer 33 to the metal substrate 31. It is desirable to maintain at 5% or more. The columnar crystals having the above thickness are preferably in the range of 20 to 90%, more preferably 50 to 90% of the entire thickness of the intermediate layer 32 with respect to the direction from the conductive carbon layer 33 to the metal substrate 31. It is desirable that it be maintained.
　これは、中間層３２の膜厚が０．０２μｍ未満の場合、中間層３２の柱状結晶構造が未発達であり、緻密性の維持が難しい。一方、中間層３２の膜厚が５μｍを超える場合、膜応力が増加し、金属基材３１との密着性が悪化することで、クラックや剥離が生じることがある。ただし、本発明の所期の効果を損なうことがなければ、中間層３２の膜厚が１０μｍ程度まで厚くても良い。さらに、上記柱状結晶の太さは、出来る限り金属基材３１と中間層３２の界面まで維持されているのが望ましい。中間層３２がかかる立体的構造を有することにより、金属基材３１及び導電性炭素層３３の間の密着性を強固にしつつ、金属基材３１の防食効果をより一層安定に維持できる。 This is because when the film thickness of the intermediate layer 32 is less than 0.02 μm, the columnar crystal structure of the intermediate layer 32 is undeveloped, and it is difficult to maintain the denseness. On the other hand, when the film thickness of the intermediate layer 32 exceeds 5 μm, the film stress increases and the adhesiveness with the metal substrate 31 is deteriorated, so that cracks and peeling may occur. However, the thickness of the intermediate layer 32 may be increased to about 10 μm as long as the intended effect of the present invention is not impaired. Furthermore, it is desirable that the thickness of the columnar crystal be maintained up to the interface between the metal base 31 and the intermediate layer 32 as much as possible. When the intermediate layer 32 has such a three-dimensional structure, the anticorrosion effect of the metal substrate 31 can be maintained more stably while strengthening the adhesion between the metal substrate 31 and the conductive carbon layer 33.
　また、中間層３２の、導電性炭素層３３側の表面は、ナノレベルで凹凸が形成されていることが好ましい。このような形態によれば、中間層３２に対する導電性炭素層３３の密着性をより一層向上させる。 In addition, the surface of the intermediate layer 32 on the side of the conductive carbon layer 33 is preferably formed with irregularities at the nano level. According to such a form, the adhesion of the conductive carbon layer 33 to the intermediate layer 32 is further improved.
　さらに、中間層３２の熱膨張率が、金属基材３１を構成する金属の熱膨張率と近い値であると、中間層３２と金属基材３１との密着性は向上する。ただし、このような形態では中間層３２と導電性炭素層３３との密着性が低下する場合がある。同様に、中間層３２の熱膨張率が導電性炭素層３３の熱膨張率と近い値であると、中間層３２と金属基材３１との密着性が低下する場合がある。これらを考慮して、中間層３２の熱膨張率（αｍｉｄ）、金属基材３１の熱膨張率（αｓｕｂ）、及び導電性炭素層３３の熱膨張率を（αｃ）は、下記関係を満足することが好ましい。 Furthermore, when the thermal expansion coefficient of the intermediate layer 32 is a value close to the thermal expansion coefficient of the metal constituting the metal substrate 31, the adhesion between the intermediate layer 32 and the metal substrate 31 is improved. However, in such a form, the adhesion between the intermediate layer 32 and the conductive carbon layer 33 may be reduced. Similarly, when the thermal expansion coefficient of the intermediate layer 32 is close to the thermal expansion coefficient of the conductive carbon layer 33, the adhesion between the intermediate layer 32 and the metal substrate 31 may be lowered. Considering these, the thermal expansion coefficient (α mid ) of the intermediate layer 32, the thermal expansion coefficient (α sub ) of the metal base 31, and the thermal expansion coefficient (α c ) of the conductive carbon layer 33 are expressed by the following relationship: Is preferably satisfied.
［数２］
αｓｕｂ ＞ αｍｉｄ ＞ αｃ [Equation 2]
α sub > α mid > α c
　なお、中間層３２は、金属基材３１の少なくとも一方の表面上に存在すれば良く、さらに金属基材３１の両表面に存在することが望ましい。導電性炭素層３３は、上述したように金属基材３１の両面に存在する場合もある。このような場合には、中間層３２は、金属基材３１と双方の導電性炭素層３３との間にそれぞれ介在することが好ましい。金属基材３１といずれか一方の導電性炭素層３３との間にのみ中間層３２が存在する場合には、当該中間層３２は、ＭＥＡ９側に配置されることとなる導電性炭素層３３側に存在することが好ましい。 The intermediate layer 32 only needs to be present on at least one surface of the metal substrate 31, and is desirably present on both surfaces of the metal substrate 31. As described above, the conductive carbon layer 33 may be present on both surfaces of the metal base 31. In such a case, the intermediate layer 32 is preferably interposed between the metal base 31 and both conductive carbon layers 33, respectively. When the intermediate layer 32 exists only between the metal substrate 31 and one of the conductive carbon layers 33, the intermediate layer 32 is disposed on the MEA 9 side. It is preferable that it exists in.
　次に、導電部材を製造するための好ましい実施形態を記載するが、本発明の技術的範囲は下記の形態のみには限定されない。また、金属セパレータ５を構成する導電部材の各構成要素の材質などの諸条件については、上述した通りであるため、ここでは説明を省略する。 Next, a preferred embodiment for manufacturing a conductive member will be described, but the technical scope of the present invention is not limited to the following embodiment. Moreover, since various conditions, such as the material of each component of the electrically-conductive member which comprises the metal separator 5, are as above-mentioned, description is abbreviate | omitted here.
　まず、金属基材３１の構成材料として、所望の厚さのアルミニウム板、又はその合金板、チタン板、ステンレス板などを準備する。次いで、適当な溶媒を用いて、準備した金属基材３１の構成材料の表面の脱脂及び洗浄処理を行う。溶媒としては、エタノール、エーテル、アセトン、イソプロピルアルコール、トリクロロエチレン及び苛性アルカリ剤などを用いることができる。脱脂及び洗浄処理としては、超音波洗浄などが挙げられる。超音波洗浄の条件としては、処理時間が１～１０分間程度、周波数が３０～５０ｋＨｚ程度、及び電力が３０～５０Ｗ程度である。 First, as a constituent material of the metal substrate 31, an aluminum plate having a desired thickness, an alloy plate thereof, a titanium plate, a stainless steel plate, or the like is prepared. Next, the surface of the constituent material of the prepared metal base 31 is degreased and cleaned using an appropriate solvent. As the solvent, ethanol, ether, acetone, isopropyl alcohol, trichloroethylene, a caustic agent, or the like can be used. Examples of the degreasing and cleaning treatment include ultrasonic cleaning. The ultrasonic cleaning conditions are a processing time of about 1 to 10 minutes, a frequency of about 30 to 50 kHz, and a power of about 30 to 50 W.
　続いて、金属基材３１の構成材料の表面に形成されている酸化皮膜の除去を行う。酸化皮膜を除去するための手法としては、酸による洗浄処理、電位印加による溶解処理、又はイオンボンバード処理などが挙げられる。その他、アルカリ浸漬洗浄、アルカリによる酸化皮膜除去(アルカリエッチング)、ふっ酸混酸液による表面活性化を行い、その後亜鉛置換浴にてジンケート処理を行う方法が好ましく使用される。ジンケート処理条件は、特に制限されないが、例えば、浴温度１０～４０℃、浸漬時間２０～９０秒である。なお、上記酸化皮膜の除去工程は省略されても良い。 Subsequently, the oxide film formed on the surface of the constituent material of the metal base 31 is removed. Examples of the method for removing the oxide film include a cleaning treatment with an acid, a dissolution treatment by applying a potential, or an ion bombardment treatment. In addition, a method in which alkali immersion cleaning, removal of an oxide film with alkali (alkali etching), surface activation with a hydrofluoric acid mixed acid solution, and subsequent zincate treatment in a zinc substitution bath is preferably used. The conditions for the zincate treatment are not particularly limited. For example, the bath temperature is 10 to 40 ° C. and the immersion time is 20 to 90 seconds. Note that the oxide film removing step may be omitted.
　上記処理は、金属板の少なくとも中間層を形成する面について行うことが好ましいが、より好ましくは金属板の両面について行う。 The treatment is preferably performed on at least the surface of the metal plate on which the intermediate layer is formed, but more preferably on both surfaces of the metal plate.
　次に、上記処理を施した金属基材３１の構成材料の表面に、導電性炭素層３３を成膜する。例えば、上述した導電性炭素層３３の構成材料（例えば、グラファイト）をターゲットとして、金属基材３１上に導電性炭素を含む層を原子レベルで積層することにより、導電性炭素層３３を形成することができる。これにより、直接付着した導電性炭素層３３と金属基材３１との界面及びその近傍は、分子間力や僅かな炭素原子の進入によって、長期間にわたって密着性が保持される。 Next, a conductive carbon layer 33 is formed on the surface of the constituent material of the metal base 31 subjected to the above-described treatment. For example, the conductive carbon layer 33 is formed by laminating a layer containing conductive carbon on the metal substrate 31 at the atomic level using the constituent material (for example, graphite) of the conductive carbon layer 33 described above as a target. be able to. As a result, the adhesion between the interface between the conductive carbon layer 33 and the metal substrate 31 directly adhered thereto and the vicinity thereof is maintained for a long period of time due to intermolecular force and the entry of a few carbon atoms.
　また、上記の処理を施した金属基材３１の表面に、中間層３２、更に導電性炭素層３３を成膜するには、導電性炭素層３３の成膜工程の前に、金属基材３１の少なくとも一方の表面に中間層３２を成膜する工程を行う。この際、中間層３２を成膜する手法としては、導電性炭素層３３の成膜について後述するのと同様の手法が採用される。ただし、ターゲットを中間層３２の構成材料に変更する必要がある。 In order to form the intermediate layer 32 and the conductive carbon layer 33 on the surface of the metal base 31 subjected to the above-described treatment, the metal base 31 is formed before the conductive carbon layer 33 is formed. A step of forming the intermediate layer 32 on at least one surface of the substrate is performed. At this time, as a method for forming the intermediate layer 32, the same method as described later for the formation of the conductive carbon layer 33 is employed. However, it is necessary to change the target to the constituent material of the intermediate layer 32.
　特に本実施形態では、中間層３２の成膜時において、負のバイアス電圧を低い値から高い値へ変化させることが好ましい。具体的には、後述する実施例I－８のように中間層３２の成膜時の初期では、金属基材３１との界面の粗さを悪くしないように低いバイアス電圧（０Ｖ超であれば良く、０Ｖ超～５０Ｖ）で成膜を開始する。その後、バイアス電圧を高い値（通常５０～５００Ｖ、好ましくは１００～２５０Ｖ）に移行させ、柱状結晶を太く成長させれば良い。そして、最適な柱状結晶構造は、予備実験等を通じてを制御することができる。 In particular, in this embodiment, it is preferable to change the negative bias voltage from a low value to a high value when the intermediate layer 32 is formed. Specifically, as in Example I-8 to be described later, at the initial stage of film formation of the intermediate layer 32, a low bias voltage (if it exceeds 0 V is selected so as not to deteriorate the roughness of the interface with the metal substrate 31. The film formation is started at 0V to 50V. Thereafter, the bias voltage is shifted to a high value (usually 50 to 500 V, preferably 100 to 250 V) to grow the columnar crystal thickly. The optimum columnar crystal structure can be controlled through preliminary experiments and the like.
　なお、上記したように中間層３２の成膜時の初期では、金属基材３１との界面の粗さを悪くしないように低いバイアス電圧で成膜を開始すれば良く、例えば、最初０Ｖ超～５０Ｖとする。そして、その後、例えば、１２０Ｖ⇒９０Ｖ⇒２００Ｖのように高い値から低い値に変化する領域があっても何ら問題ない。これは、バイアス電圧が低い値のとき、柱状晶の柱径は小さくなり、高い値のとき柱径は大きくなり、その後、低い値等に変化させても高い値のときの柱径を維持できるためである。即ち、中間層３２の成膜時の初期では、金属基材３１との界面の粗さを悪くしないように低いバイアス電圧で成膜を開始し、その後バイアス電圧を高い値に移行させることで、その後の電圧に変化によらず、柱状結晶を太く成長させることができる。そして、導電性炭素層３３は、中間層３２の太い柱状結晶に沿って形成される。 As described above, at the initial stage of film formation of the intermediate layer 32, film formation may be started at a low bias voltage so as not to deteriorate the roughness of the interface with the metal substrate 31, and for example, initially, it may be over 0V to 50V. After that, there is no problem even if there is a region where the value changes from a high value to a low value, for example, 120V → 90V → 200V. This is because when the bias voltage is a low value, the column diameter of the columnar crystal is small, when the bias voltage is high, the column diameter is large, and after that, the column diameter at a high value can be maintained even if it is changed to a low value or the like. Because. That is, at the initial stage of film formation of the intermediate layer 32, the film formation is started at a low bias voltage so as not to deteriorate the roughness of the interface with the metal substrate 31, and then the bias voltage is shifted to a high value. Regardless of the change in voltage thereafter, the columnar crystal can be grown thick. The conductive carbon layer 33 is formed along the thick columnar crystal of the intermediate layer 32.
　製造方法として、装置の設定値を変えるだけの簡便な方法により、中間層３２が柱状結晶構造を有しており、最表面に突起状粒子３３ａが存在している構造の導電部材を得ることができる。特に、最初に金属基材３１上に中間層３２を形成する際、最初から柱を太くするためには、金属基材３１表面に加わるエネルギーが高くなるため、密着不良をおこす場合がある。したがって、金属基材３１側の柱状結晶は、導電性炭素層３３側に比べ細い方が好ましい。そのため、中間層３２の成膜時の初期では、金属基材３１との界面の粗さを悪くしないように低いバイアス電圧で成膜を開始するのが良い。しかしながら、その後の柱状結晶の太さについては、出来る限り太い柱状結晶が、導電性炭素層３３と中間層３２の界面まで維持されているのが望ましい。そのため、その後バイアス電圧を高い値に移行させ、柱状結晶を太く成長させる。そして、導電性炭素層３３は、中間層３２の柱状結晶に沿って成長する。かかる製造方法により、中間層３２の柱状結晶を導電性炭素層３３との界面まで太くし、その上に形成される導電性炭素層３３における隙間や欠陥を低減することができる。 As a manufacturing method, it is possible to obtain a conductive member having a structure in which the intermediate layer 32 has a columnar crystal structure and the protruding particles 33a are present on the outermost surface by a simple method of changing the set value of the apparatus. it can. In particular, when the intermediate layer 32 is formed on the metal base 31 for the first time, in order to thicken the column from the beginning, energy applied to the surface of the metal base 31 is increased, which may cause poor adhesion. Accordingly, the columnar crystal on the metal base 31 side is preferably thinner than the conductive carbon layer 33 side. Therefore, at the initial stage of forming the intermediate layer 32, it is preferable to start the film formation with a low bias voltage so as not to deteriorate the roughness of the interface with the metal substrate 31. However, as for the thickness of the columnar crystal thereafter, it is desirable that the columnar crystal as thick as possible is maintained up to the interface between the conductive carbon layer 33 and the intermediate layer 32. Therefore, after that, the bias voltage is shifted to a high value to grow the columnar crystal thickly. The conductive carbon layer 33 grows along the columnar crystal of the intermediate layer 32. With this manufacturing method, the columnar crystals of the intermediate layer 32 can be thickened to the interface with the conductive carbon layer 33, and gaps and defects in the conductive carbon layer 33 formed thereon can be reduced.
　上記した負のバイアス電圧を低い値から高い値へ変化させる手法としては、スパッタリング法が好ましい。そして、導電性炭素層３３もスパッタリング法により形成されることが好ましい。さらに、プロセス上、その前に行う中間層３２の成膜についても、同様なドライプロセス、特にスパッタリング法にて行うことが望ましい。この場合、中間層３２は、導電性炭素層３３と同方式及び同装置にて成膜できるため、製造プロセス費を低くすることが可能となる。 As a method for changing the negative bias voltage from a low value to a high value, a sputtering method is preferable. The conductive carbon layer 33 is also preferably formed by a sputtering method. Further, in the process, the intermediate layer 32 formed before that is preferably formed by a similar dry process, particularly by a sputtering method. In this case, since the intermediate layer 32 can be formed by the same method and the same apparatus as the conductive carbon layer 33, the manufacturing process cost can be reduced.
　また、上記中間層３２を成膜する工程では、金属基材３１の表面に研磨処理等の前処理を施した後、金属基材３１の表面にスパッタリング法により皮膜を形成するのが望ましい。これは、研磨処理により金属基材３１の表面粗さが小さくなると、柱状晶の核生成サイトの数が少なくなり、個々の柱状晶の柱径は大きくなるためである。ここで、前処理としては、研磨処理の他にも、一般的に実施されている処理が広く採用できる。例えば、電解研磨、ラップ処理、マイクロショット処理などが適用可能である。 Further, in the step of forming the intermediate layer 32, it is desirable that a film is formed on the surface of the metal base 31 by sputtering after the surface of the metal base 31 is subjected to pretreatment such as polishing. This is because when the surface roughness of the metal substrate 31 is reduced by the polishing treatment, the number of columnar crystal nucleation sites is reduced and the column diameter of each columnar crystal is increased. Here, as the pretreatment, in addition to the polishing treatment, a treatment that is generally performed can be widely adopted. For example, electrolytic polishing, lapping treatment, microshot treatment, etc. can be applied.
　次に、上記の処理を施した金属基材３１の構成材料の表面に、中間層３２及び導電性炭素層３３を順に成膜する。例えば、まず、上述した中間層３２の構成材料（例えば、クロム）をターゲットとして、金属基材３１（例えば、アルミニウムやその合金）の両表面上に、上記したバイアス変化により、クロム中間層３２を積層する。次に、導電性炭素層３３の構成材料（例えば、グラファイト）を順にターゲットとして、中間層３２表面上に、導電性炭素を含む層３３を原子レベルで積層する。これにより、中間層３２、導電性炭素層３３を順次形成することができる。さらに、直接付着した導電性炭素層３３と中間層３２と金属基材３１との界面及びその近傍は、分子間力や僅かな炭素原子の進入によって、長期間にわたって密着性が保持される。 Next, the intermediate layer 32 and the conductive carbon layer 33 are sequentially formed on the surface of the constituent material of the metal base 31 subjected to the above treatment. For example, first, the chromium intermediate layer 32 is formed on both surfaces of the metal base 31 (for example, aluminum or an alloy thereof) by the above-described bias change using the constituent material of the intermediate layer 32 (for example, chromium) as a target. Laminate. Next, the layer 33 containing conductive carbon is laminated on the surface of the intermediate layer 32 on the surface of the intermediate layer 32 using the constituent material (for example, graphite) of the conductive carbon layer 33 as a target in order. Thereby, the intermediate layer 32 and the conductive carbon layer 33 can be formed sequentially. Furthermore, the adhesion between the directly attached conductive carbon layer 33, intermediate layer 32, and metal base 31 and its vicinity is maintained for a long period of time due to intermolecular forces and the ingress of slight carbon atoms.
　中間層３２及び導電性炭素層３３を積層するのに好適に用いられる手法としては、スパッタリング法もしくはイオンプレーティング法などの物理気相成長（ＰＶＤ）法、又はフィルタードカソーディックバキュームアーク（ＦＣＶＡ）法などのイオンビーム蒸着法などが挙げられる。スパッタリング法としては、マグネトロンスパッタリング法、アンバランスドマグネトロンスパッタリング（ＵＢＭＳ）法、デュアルマグネトロンスパッタ法、ＥＣＲスパッタリング法などが挙げられる。また、イオンプレーティング法としては、アークイオンプレーティング法などが挙げられる。なかでも、スパッタリング法及びイオンプレーティング法を用いることが好ましく、スパッタリング法を用いることが特に好ましい。このような手法によれば、水素含有量の少ない炭素層を形成することができる。その結果、炭素原子同士の結合（ｓｐ２混成炭素）の割合を増加させることができ、優れた導電性が達成される。これに加えて、比較的低温で成膜が可能であり、金属基材３１へのダメージを最小限に抑えることができるという利点もある。さらに、スパッタリング法によれば、バイアス電圧等を制御することで、上記柱状結晶構造を有する中間層３２を得ることができる。 As a method suitably used for laminating the intermediate layer 32 and the conductive carbon layer 33, a physical vapor deposition (PVD) method such as a sputtering method or an ion plating method, or a filtered cathodic vacuum arc (FCVA) is used. And ion beam deposition methods. Examples of the sputtering method include a magnetron sputtering method, an unbalanced magnetron sputtering (UBMS) method, a dual magnetron sputtering method, and an ECR sputtering method. Examples of the ion plating method include an arc ion plating method. Especially, it is preferable to use sputtering method and an ion plating method, and it is especially preferable to use sputtering method. According to such a method, a carbon layer having a low hydrogen content can be formed. As a result, the ratio of bonds between carbon atoms (sp 2 hybrid carbon) can be increased, and excellent conductivity is achieved. In addition to this, the film can be formed at a relatively low temperature, and there is an advantage that damage to the metal substrate 31 can be minimized. Furthermore, according to the sputtering method, the intermediate layer 32 having the columnar crystal structure can be obtained by controlling the bias voltage or the like.
　上述のように、中間層３２及び導電性炭素層３３の成膜をスパッタリング法により行う場合には、スパッタリング時に金属基材３１に対して負のバイアス電圧を印加すると良い。このような形態によれば、イオン照射効果によって、上記柱状結晶構造を有する中間層３２やグラファイトクラスタが緻密に集合した導電性炭素層３３が成膜される。このような中間層３２は金属基材３１の防食効果を高めることができ、アルミニウムのような腐食しやすい金属の場合でも、金属基材３１として適用できる。さらに、導電性炭素層３３は優れた導電性を発揮することから、他の部材（例えば、ＭＥＡ９）との接触抵抗の小さい金属セパレータ５が提供される。 As described above, when the intermediate layer 32 and the conductive carbon layer 33 are formed by the sputtering method, it is preferable to apply a negative bias voltage to the metal substrate 31 during the sputtering. According to such a configuration, the intermediate carbon layer 32 having the columnar crystal structure and the conductive carbon layer 33 in which graphite clusters are densely assembled are formed by the ion irradiation effect. Such an intermediate layer 32 can enhance the anticorrosive effect of the metal substrate 31 and can be applied as the metal substrate 31 even in the case of a metal that is easily corroded such as aluminum. Furthermore, since the conductive carbon layer 33 exhibits excellent conductivity, the metal separator 5 having a low contact resistance with other members (for example, the MEA 9) is provided.
　当該形態において、印加される負のバイアス電圧の絶対値は特に制限されず、導電性炭素層３３を成膜可能な電圧が採用される。印加される電圧の大きさは、好ましくは５０～５００Ｖであり、より好ましくは１００～３００Ｖである。一方、中間層３２では、上記の通り、成膜時における負のバイアス電圧を低い値から高い値へ変化させる手法が好適である。具体的には、後述する実施例のように中間層３２の成膜時の初期では、低いバイアス電圧（０Ｖ超～５０Ｖ）で成膜を開始し、その後バイアス電圧を高い値（通常５０～５００Ｖ、好ましくは１００～２５０Ｖ）に移行させ柱状結晶構造を太く成長させれば良い。なお、上記したように、中間層３２の成膜時の初期では、低いバイアス電圧で成膜を開始すれば良く、その後、１２０Ｖ⇒９０Ｖ⇒２００Ｖのように高い値から低い値に変化する領域があっても何ら問題ない。 In this embodiment, the absolute value of the negative bias voltage to be applied is not particularly limited, and a voltage capable of forming the conductive carbon layer 33 is employed. The magnitude of the applied voltage is preferably 50 to 500V, more preferably 100 to 300V. On the other hand, for the intermediate layer 32, as described above, a method of changing the negative bias voltage during film formation from a low value to a high value is suitable. Specifically, as in the examples described later, in the initial stage of film formation of the intermediate layer 32, film formation is started with a low bias voltage (above 0 V to 50 V), and then the bias voltage is increased to a high value (usually 50 to 500 V). (Preferably, the columnar crystal structure is grown thickly by shifting to 100 to 250 V). As described above, in the initial stage of film formation of the intermediate layer 32, film formation may be started with a low bias voltage, and thereafter, there is a region where the value changes from a high value to a low value, such as 120V → 90V → 200V. There is no problem even if it exists.
　なお、成膜時のその他の条件は特に制限されず、従来公知の知見が適宜参照される。また、ＵＢＭＳ法により導電性炭素層３３を成膜する場合には、予め同様の装置及び製法で中間層３２を形成しておき、その上に導電性炭素層３３を形成することが好ましい。これにより、金属基材３１との密着性に優れる中間層３２及び導電性炭素層３３が形成される。ただし、他の手法や装置によって中間層３２を形成し、異なる装置や製法にて導電性炭素層３３を成膜するようにしても良い。この場合であっても、金属基材３１との密着性に優れる中間層３２及び導電性炭素層３３が形成される。また、他の手法や装置によって、金属基材３１上に導電性炭素層３３を形成する場合には、中間層３２が存在しない場合であっても、金属基材３１との密着性に優れる導電性炭素層３３が形成される。 In addition, other conditions at the time of film formation are not particularly limited, and conventionally known knowledge is appropriately referred to. Further, when the conductive carbon layer 33 is formed by the UBMS method, it is preferable to form the intermediate layer 32 in advance by the same apparatus and manufacturing method, and form the conductive carbon layer 33 thereon. Thereby, the intermediate | middle layer 32 and the electroconductive carbon layer 33 which are excellent in adhesiveness with the metal base material 31 are formed. However, the intermediate layer 32 may be formed by another method or apparatus, and the conductive carbon layer 33 may be formed by a different apparatus or manufacturing method. Even in this case, the intermediate layer 32 and the conductive carbon layer 33 having excellent adhesion to the metal substrate 31 are formed. Further, when the conductive carbon layer 33 is formed on the metal base material 31 by another method or apparatus, the conductivity excellent in adhesion to the metal base material 31 even when the intermediate layer 32 is not present. The carbon layer 33 is formed.
　上述した手法によれば、金属基材３１の一方の表面に中間層３２及び導電性炭素層３３が形成される。金属基材３１の両面に中間層３２及び導電性炭素層３３が形成するには、金属基材３１の他方の表面に対して、同様の手法によって、中間層３２及び導電性炭素層３３を形成すれば良い。また、上述したのと同様の手法によれば、金属基材３１の両表面に一度に中間層３２及び導電性炭素層３３が形成された導電部材が製造される。金属基材３１の両面に中間層３２及び導電性炭素層３３が形成するには、市販の成膜装置（両面同時スパッタ成膜装置）を用いても良い。また、コスト的には有利とはいえないが、金属基材３１の一方の表面に中間層３２及び導電性炭素層３３を成膜し、ついで金属基材３１の他方の面に中間層３２及び導電性炭素層３３を順次形成しても良い。あるいは、まず、クロムをターゲットとした装置内で、金属基材３１の一方の面に中間層３２を成膜し、続いて、他方の面に中間層３２を成膜する。その後、ターゲットをカーボンに切り替えて、一方の面に形成された中間層３２上に導電性炭素層３３を成膜し、続いて、他方の面に導電性炭素層３３を成膜する。このように、金属基材３１の両表面へ中間層３２及び導電性炭素層３３を成膜する場合でも、一表面へ成膜するのと同様の手法が採用される。 According to the method described above, the intermediate layer 32 and the conductive carbon layer 33 are formed on one surface of the metal substrate 31. In order to form the intermediate layer 32 and the conductive carbon layer 33 on both surfaces of the metal substrate 31, the intermediate layer 32 and the conductive carbon layer 33 are formed on the other surface of the metal substrate 31 by the same method. Just do it. Further, according to the same method as described above, a conductive member in which the intermediate layer 32 and the conductive carbon layer 33 are formed at the same time on both surfaces of the metal base 31 is manufactured. In order to form the intermediate layer 32 and the conductive carbon layer 33 on both surfaces of the metal substrate 31, a commercially available film forming apparatus (double-sided simultaneous sputtering film forming apparatus) may be used. Although not advantageous in terms of cost, the intermediate layer 32 and the conductive carbon layer 33 are formed on one surface of the metal substrate 31, and then the intermediate layer 32 and the conductive carbon layer 33 are formed on the other surface of the metal substrate 31. The conductive carbon layer 33 may be formed sequentially. Alternatively, first, the intermediate layer 32 is formed on one surface of the metal base 31 and then the intermediate layer 32 is formed on the other surface in an apparatus using chromium as a target. Thereafter, the target is switched to carbon, and the conductive carbon layer 33 is formed on the intermediate layer 32 formed on one surface, and then the conductive carbon layer 33 is formed on the other surface. Thus, even when the intermediate layer 32 and the conductive carbon layer 33 are formed on both surfaces of the metal substrate 31, the same technique as that for forming the film on one surface is employed.
　図１９は、中間層３２及び導電性炭素層３３の少なくともいずれか一方をスパッタリング法を用いて成膜するための製造装置の平面概略図である。ここでは、スパッタリング装置として、実施例でも用いたアンバランスドマグネトロンスパッタリング法に適用し得る装置を示している。また、図２０は、中間層３２及び導電性炭素層３３の少なくともいずれか一方をアークイオンプレーティング法を用いて成膜するための製造装置の平面概略図である。但し、図１９及び図２０中には、凹凸プレス前の平板型の金属セパレータ５に替えて、既存の円盤状のウエハをセットした例を示している。 FIG. 19 is a schematic plan view of a manufacturing apparatus for depositing at least one of the intermediate layer 32 and the conductive carbon layer 33 using a sputtering method. Here, as a sputtering apparatus, an apparatus applicable to the unbalanced magnetron sputtering method used in the examples is shown. FIG. 20 is a schematic plan view of a manufacturing apparatus for forming at least one of the intermediate layer 32 and the conductive carbon layer 33 using the arc ion plating method. However, FIG. 19 and FIG. 20 show an example in which an existing disk-shaped wafer is set in place of the flat metal separator 5 before the uneven pressing.
　図１９及び図２０に示す装置３００、４００を用いてスパッタリングする場合、回転するテーブル３０１、４０１に金属セパレータ５が１枚ないし複数枚配置される。そして、各金属セパレータ５の表裏に成膜するために、各金属セパレータ５自身も、テーブルの回転軸と直行する方向に回転する。テーブル３０１、４０１及び金属セパレータ５それぞれの矢印方向は、回転軸同士が相互に直行する。 When sputtering is performed using the apparatuses 300 and 400 shown in FIGS. 19 and 20, one or more metal separators 5 are arranged on the rotating tables 301 and 401. And in order to form into a film on the front and back of each metal separator 5, each metal separator 5 itself rotates in the direction orthogonal to the rotating shaft of a table. In the arrow directions of the tables 301 and 401 and the metal separator 5, the rotation axes are orthogonal to each other.
　真空チャンバー３０３、４０３内は１０－１～１０－２Ｔｏｒｒレベルで保持され、必要に応じて、給気口３０５、４０５より、不活性ガス（Ｎ２、Ａｒ等）を導入することが出来る。真空チャンバー３０３、４０３内の所定の圧力（真空等）を制御すべく、不要なガスは排気口３０７、４０７より適宜排気される。 The vacuum chambers 303 and 403 are maintained at a level of 10 −1 to 10 −2 Torr, and an inert gas (N 2 , Ar, etc.) can be introduced from the air supply ports 305 and 405 as necessary. In order to control a predetermined pressure (such as vacuum) in the vacuum chambers 303 and 403, unnecessary gas is appropriately exhausted from the exhaust ports 307 and 407.
　真空チャンバー３０３、４０３及び各金属セパレータ５を保持するテーブル３０１、４０１自体には温調設備が接続され、温度調節することが出来る。 Temperature control equipment is connected to the vacuum chambers 303 and 403 and the tables 301 and 401 themselves holding the metal separators 5 so that the temperature can be adjusted.
　まず、各金属セパレータ５表面をＡｒイオンボンバードにて金属セパレータ５表層に存在する酸化皮膜を取り除く。酸化皮膜は数オングストロームの厚さで形成されるため、除去時間は数秒～数分で良い。本実施形態では導電性炭素層３３の成膜前に中間層３２としてＣｒを配置する。このため、チャンバー３０１、４０１内にはＣｒターゲット３０９、４０９を配置する。Ｃｒによる中間層３２形成後、続けて同一チャンバー３０１、４０１内に配置したカーボンターゲット３１１、４１１を用いて導電性炭素層３３を形成する。後述する実施例I－８のように、中間層３２の形成においては、バイアス電圧等を所定の値で変えることなく一定で行っても良いし、２回又はそれ以上変更して成膜を行っても良い。この際、バイアス電圧を連続的に変えながら成膜しても良い。この他にも、各金属セパレータ５のバイアス電圧や温度、真空度等を変更して続けて形成することが出来る（実施例I－８参照）。導電性炭素層３３の形成においても、バイアス電圧等を所定の値で変えることなく一定で行っても良いし、２回又はそれ以上変更して成膜を行っても良い。導電性炭素層３３は、層を形成する炭素分子内に水素が存在することで、導電性が落ちる傾向があることから、固体（カーボングラファイトなど）をターゲットとするスパッタが好ましい。 First, the oxide film present on the surface of the metal separator 5 is removed from the surface of each metal separator 5 with Ar ion bombardment. Since the oxide film is formed with a thickness of several angstroms, the removal time may be several seconds to several minutes. In the present embodiment, Cr is disposed as the intermediate layer 32 before the conductive carbon layer 33 is formed. For this reason, Cr targets 309 and 409 are disposed in the chambers 301 and 401, respectively. After the formation of the intermediate layer 32 of Cr, the conductive carbon layer 33 is formed using the carbon targets 311 and 411 disposed in the same chambers 301 and 401 continuously. As in Example I-8, which will be described later, the intermediate layer 32 may be formed without changing the bias voltage or the like at a predetermined value, or may be formed twice or more times. May be. At this time, the film may be formed while continuously changing the bias voltage. In addition, the metal separator 5 can be continuously formed by changing the bias voltage, temperature, degree of vacuum, etc. (see Example I-8). The formation of the conductive carbon layer 33 may be performed without changing the bias voltage or the like at a predetermined value, or may be performed twice or more. The conductive carbon layer 33 is preferably sputtered using a solid (such as carbon graphite) as a target because the conductivity tends to decrease due to the presence of hydrogen in the carbon molecules forming the layer.
　導電性炭素層３３を図２０に示す装置を用いて、アークイオンプレーティング法で形成する場合（実施例I－６参照）、ターゲットは図１９と同様に、カーボンターゲット４１１を使用することが出来る。そして、アーク放電向けの別の蒸着源４１３を配置することで、同一チャンバ４０１内で真空度を落とすことなしに成膜することが可能である。図２０に示す装置を用いたＡＩＰ法による導電性炭素層３３の形成においても、所定の特性を有する導電性炭素層３３を得るために、アーク電源４１５の電圧、電流や真空度、温度、バイアス電圧等を変えることなく一定で行っても良いし、適宜を変更しても良い。 When the conductive carbon layer 33 is formed by the arc ion plating method using the apparatus shown in FIG. 20 (see Example I-6), the carbon target 411 can be used as the target as in FIG. . By disposing another vapor deposition source 413 for arc discharge, it is possible to form a film in the same chamber 401 without reducing the degree of vacuum. Also in the formation of the conductive carbon layer 33 by the AIP method using the apparatus shown in FIG. 20, in order to obtain the conductive carbon layer 33 having predetermined characteristics, the voltage, current, vacuum degree, temperature, and bias of the arc power source 415 are obtained. It may be performed without changing the voltage or the like, or may be changed as appropriate.
　導電性炭素層３３の形成は、例えば、図１９又は図２０の装置を用いて、中間層３２の蒸着後に、ターゲットを取り替えた後、バイアス電圧、温度、真空度及び供給ガス量の少なくとも１つ以上を変えて、同一バッチで形成するのが望ましい。これは、導電性炭素層３３は、中間層３２の成膜後に連続的に形成することができ、さらに同一の成膜プロセス上で形成できるため、低コストになる点で優れている。 The conductive carbon layer 33 is formed by, for example, using the apparatus shown in FIG. 19 or FIG. 20, after the deposition of the intermediate layer 32, after changing the target, and at least one of bias voltage, temperature, vacuum degree, and supply gas amount. It is desirable to change the above and form the same batch. This is excellent in that the conductive carbon layer 33 can be continuously formed after the intermediate layer 32 is formed, and can be formed on the same film formation process, so that the cost is low.
　本実施形態では、中間層３２及び導電性炭素層３３は、図１９に示す装置を用いてスパッタリングにて形成するか（実施例I－１～５、８～９）、図２０に示す装置を用いてＡＩＰ法（実施例I－６参照）もしくはＥＣＲスパッタリング法（実施例I－７参照）にて形成するのが望ましい。これは、スパッタリングやＡＩＰ法を使うことで、導電性炭素層３３の一方の面から他方の面への導電パスが確保されることにより、優れた導電性を十分に確保しつつ、耐食性がより一層向上した導電部材が提供することができる。また、スパッタリングやＡＩＰ法を使うことで、優れた導電性を十分に確保しつつ、接触抵抗の増加を抑制する中間層を形成することができる。 In this embodiment, the intermediate layer 32 and the conductive carbon layer 33 are formed by sputtering using the apparatus shown in FIG. 19 (Examples I-1 to 5 and 8 to 9), or the apparatus shown in FIG. It is desirable to use the AIP method (see Example I-6) or the ECR sputtering method (see Example I-7). This is because, by using a sputtering or AIP method, a conductive path from one surface of the conductive carbon layer 33 to the other surface is secured, so that excellent electrical conductivity is sufficiently secured and corrosion resistance is further improved. A further improved conductive member can be provided. Further, by using sputtering or the AIP method, it is possible to form an intermediate layer that suppresses an increase in contact resistance while sufficiently ensuring excellent conductivity.
　中間層３２、導電性炭素層３３の成膜では、固体ソース（例えば、グラファイトカーボン）が望ましい。ガスソースでは、現在用いられているガス種では品質の良いものができにくい。
これは中間層３２及び導電性炭素層３３内に水素が入り、導電性が低下するためである。なお、ターゲット３０９、３１１、４０９、４１１、４１３のサイズ並びに個数は、金属セパレータ５のサイズや処理量等によって適宜調整できる。 In forming the intermediate layer 32 and the conductive carbon layer 33, a solid source (eg, graphite carbon) is desirable. With a gas source, it is difficult to produce a high quality gas type currently used.
This is because hydrogen enters the intermediate layer 32 and the conductive carbon layer 33 and the conductivity decreases. Note that the size and number of the targets 309, 311, 409, 411, and 413 can be adjusted as appropriate depending on the size and the processing amount of the metal separator 5.
　本実施形態の中間層３２及び導電性炭素層３３は、金属セパレータ５だけでなく、導電性と耐食性が必要とされる部品の表面であれば、何処にでも適応が可能である。例えば、複数のセルを積層したスタック２０の両端に配置する集電板３０、４０（図１４参照）や、電圧をモニタリングする際の端子接続部（図１４の出力端子３７、４７参照）などが挙げられる。 The intermediate layer 32 and the conductive carbon layer 33 of the present embodiment can be applied anywhere as long as they are not only the metal separator 5 but also the surface of a component that requires conductivity and corrosion resistance. For example, current collecting plates 30 and 40 (see FIG. 14) disposed at both ends of the stack 20 in which a plurality of cells are stacked, terminal connection portions (see output terminals 37 and 47 in FIG. 14) for monitoring voltage, etc. Can be mentioned.
　本実施形態の導電部材は、種々の用途に用いられる。その代表例が図１に示すセルユニット１の金属セパレータ５である。ただし、本実施形態の導電部材の用途はこれに限られない。例えば、ＰＥＦＣ以外にも、リン酸形燃料電池（ＰＡＦＣ）、溶融炭酸塩形燃料電池（ＭＣＦＣ）、固体電解質形燃料電池（ＳＯＦＣ）又はアルカリ形燃料電池（ＡＦＣ）などの各種の燃料電池用セパレータとしても使用可能である。また、燃料電池用セパレータ以外にも、導電性・耐食性の両立が求められている各種の用途に用いられる。本実施形態の導電部材が用いられる用途としては、例えば、他の燃料電池部品（集電板、バスバー、ガス拡散基体、ＭＥＡ）、電子部品の接点などが挙げられる。 The conductive member of this embodiment is used for various purposes. A typical example is the metal separator 5 of the cell unit 1 shown in FIG. However, the use of the conductive member of the present embodiment is not limited to this. For example, in addition to PEFC, various fuel cell separators such as phosphoric acid fuel cell (PAFC), molten carbonate fuel cell (MCFC), solid electrolyte fuel cell (SOFC) or alkaline fuel cell (AFC) Can also be used. In addition to the fuel cell separator, it is used in various applications that require both conductivity and corrosion resistance. Examples of applications in which the conductive member of the present embodiment is used include other fuel cell components (current collector plate, bus bar, gas diffusion base, MEA), contacts of electronic components, and the like.
　また、本実施形態の導電部材は、湿潤環境及び通電環境の下で使用することができる。このような環境下で用いると、導電性及び耐食性の両立を図るという本発明の作用効果が顕著に発現する。なお、「湿潤環境」とは、導電部材と接触する雰囲気の相対湿度が３０ＲＨ以上の環境をいう。当該相対湿度は、好ましくは３０％ＲＨ以上であり、より好ましくは６０％ＲＨ以上であり、特に好ましくは１００％ＲＨ以上である。また、本実施形態の導電部材が用いられる「通電環境」とは、０．００１Ａ／ｃｍ２以上の電流密度で、導電部材を電流が流れる環境をいう。当該電流密度は、好ましくは０．０１Ａ／ｃｍ２以上である。 In addition, the conductive member of the present embodiment can be used in a wet environment and an energized environment. When used in such an environment, the effect of the present invention of achieving both conductivity and corrosion resistance is remarkably exhibited. The “humid environment” refers to an environment where the relative humidity of the atmosphere in contact with the conductive member is 30 RH or higher. The relative humidity is preferably 30% RH or more, more preferably 60% RH or more, and particularly preferably 100% RH or more. The “energization environment” in which the conductive member of the present embodiment is used refers to an environment in which current flows through the conductive member at a current density of 0.001 A / cm 2 or more. The current density is preferably 0.01 A / cm 2 or more.
　以下、図１～４、１３、１４等を参照しつつ、本実施形態の導電部材から構成される金属セパレータ５を用いたＰＥＦＣの構成要素について説明する。ただし、本実施形態はセパレータを構成する導電部材に特徴を有するものである。よって、セルユニット１における金属セパレータ５の形状等の具体的な形態や、燃料電池を構成する金属セパレータ５以外の部材の具体的な形態については、従来公知の知見を参照しつつ、適宜、改変が施される。図１３は、図１の燃料電池のセルユニット構成を複数積層してなる燃料電池スタック構成の一例を説明するための断面概略図であり、図１４は、図１３の燃料電池スタック構成の斜視図である。 Hereinafter, components of the PEFC using the metal separator 5 formed of the conductive member of the present embodiment will be described with reference to FIGS. 1 to 4, 13, 14 and the like. However, the present embodiment is characterized by the conductive member constituting the separator. Therefore, the specific form such as the shape of the metal separator 5 in the cell unit 1 and the specific form of members other than the metal separator 5 constituting the fuel cell are appropriately modified with reference to conventionally known knowledge. Is given. 13 is a schematic cross-sectional view for explaining an example of a fuel cell stack configuration in which a plurality of cell unit configurations of the fuel cell of FIG. 1 are stacked, and FIG. 14 is a perspective view of the fuel cell stack configuration of FIG. It is.
　［電解質層］
　電解質膜２は、例えば、図１、１３に示すように固体高分子電解質膜２から構成される。固体高分子電解質膜２は、ＰＥＦＣの運転時にアノード触媒層３ａで生成したプロトンを膜厚方向に沿ってカソード触媒層３ｂへと選択的に透過させる機能を有する。また、固体高分子電解質膜２は、アノード側に供給される燃料ガス５ａｇとカソード側に供給される酸化剤ガス５ｂｇとを混合させないための隔壁としての機能をも有する。 [Electrolyte layer]
The electrolyte membrane 2 is composed of a solid polymer electrolyte membrane 2 as shown in FIGS. The solid polymer electrolyte membrane 2 has a function of selectively transmitting protons generated in the anode catalyst layer 3a during PEFC operation to the cathode catalyst layer 3b along the film thickness direction. The solid polymer electrolyte membrane 2 also has a function as a partition wall for preventing the fuel gas 5ag supplied to the anode side and the oxidant gas 5bg supplied to the cathode side from being mixed.
　固体高分子電解質膜２は、構成材料であるイオン交換樹脂の種類によって、フッ素系高分子電解質膜と炭化水素系高分子電解質膜とに大別される。フッ素系高分子電解質膜を構成するイオン交換樹脂としては、例えば、ナフィオン（登録商標、デュポン社製）、アシプレックス（登録商標、旭化成株式会社製）、フレミオン（登録商標、旭硝子株式会社製）等のパーフルオロカーボンスルホン酸系ポリマー、パーフルオロカーボンホスホン酸系ポリマー、トリフルオロスチレンスルホン酸系ポリマー、エチレンテトラフルオロエチレン－ｇ－スチレンスルホン酸系ポリマー、エチレン－テトラフルオロエチレン共重合体、ポリビニリデンフルオリド－パーフルオロカーボンスルホン酸系ポリマーなどが挙げられる。耐熱性、化学的安定性などの発電性能を向上させるという観点からは、これらのフッ素系高分子電解質膜が好ましく用いられ、特に好ましくはパーフルオロカーボンスルホン酸系ポリマーから構成されるフッ素系高分子電解質膜が用いられる。 The solid polymer electrolyte membrane 2 is roughly classified into a fluorine-based polymer electrolyte membrane and a hydrocarbon-based polymer electrolyte membrane depending on the type of ion exchange resin that is a constituent material. Examples of ion exchange resins constituting the fluorine-based polymer electrolyte membrane include Nafion (registered trademark, manufactured by DuPont), Aciplex (registered trademark, manufactured by Asahi Kasei Co., Ltd.), Flemion (registered trademark, manufactured by Asahi Glass Co., Ltd.), and the like. Perfluorocarbon sulfonic acid polymer, perfluorocarbon phosphonic acid polymer, trifluorostyrene sulfonic acid polymer, ethylene tetrafluoroethylene-g-styrene sulfonic acid polymer, ethylene-tetrafluoroethylene copolymer, polyvinylidene fluoride- Examples include perfluorocarbon sulfonic acid polymers. From the viewpoint of improving power generation performance such as heat resistance and chemical stability, these fluorine-based polymer electrolyte membranes are preferably used, and particularly preferably fluorine-based polymer electrolytes composed of perfluorocarbon sulfonic acid polymers. A membrane is used.
　炭化水素系電解質として、具体的には、スルホン化ポリエーテルスルホン（Ｓ－ＰＥＳ）、スルホン化ポリアリールエーテルケトン、アルキルスルホン化ポリベンズイミダゾール、アルキルホスホン化ポリベンズイミダゾール、スルホン化ポリスチレン、スルホン化ポリエーテルエーテルケトン（Ｓ－ＰＥＥＫ）、スルホン化ポリフェニレン（Ｓ－ＰＰＰ）などが挙げられる。原料が安価で製造工程が簡便であり、かつ材料の選択性が高いといった製造上の観点からは、これらの炭化水素系高分子電解質膜が好ましく用いられる。なお、上述したイオン交換樹脂は、一種のみが単独で用いられてもよいし、二種以上が併用されても良い。また、上述した材料のみに制限されず、その他の材料が用いられても良い。 Specific examples of hydrocarbon electrolytes include sulfonated polyethersulfone (S-PES), sulfonated polyaryletherketone, alkylsulfonated polybenzimidazole, alkylphosphonated polybenzimidazole, sulfonated polystyrene, and sulfonated poly Examples include ether ether ketone (S-PEEK) and sulfonated polyphenylene (S-PPP). These hydrocarbon polymer electrolyte membranes are preferably used from the viewpoint of production such that the raw material is inexpensive, the production process is simple, and the material selectivity is high. In addition, as for the ion exchange resin mentioned above, only 1 type may be used independently and 2 or more types may be used together. Moreover, it is not restricted only to the material mentioned above, Other materials may be used.
　電解質膜２の厚さは、得られる燃料電池の特性を考慮して適宜決定すれば良く、特に制限されない。電解質層の厚さは、通常は５μｍ～３００μｍ程度である。電解質層の厚さがこのような範囲内の値であると、成膜時の強度や使用時の耐久性及び使用時の出力特性のバランスが適切に制御される。 The thickness of the electrolyte membrane 2 may be appropriately determined in consideration of the characteristics of the obtained fuel cell, and is not particularly limited. The thickness of the electrolyte layer is usually about 5 μm to 300 μm. When the thickness of the electrolyte layer is within such a range, the balance of strength during film formation, durability during use, and output characteristics during use is appropriately controlled.
　［触媒層］
　図１、１３に示す触媒層３（アノード触媒層３ａ、カソード触媒層３ｂ）は、実際に電池反応が進行する層である。具体的には、アノード触媒層３ａでは水素の酸化反応が進行し、カソード触媒層３ｂでは酸素の還元反応が進行する。触媒層３は、触媒成分、触媒成分を担持する導電性の触媒担体及び電解質を含有する。以下、触媒担体に触媒成分が担持されてなる複合体を「電極触媒」とも称する。 [Catalyst layer]
The catalyst layers 3 (the anode catalyst layer 3a and the cathode catalyst layer 3b) shown in FIGS. 1 and 13 are layers in which the cell reaction actually proceeds. Specifically, the oxidation reaction of hydrogen proceeds in the anode catalyst layer 3a, and the reduction reaction of oxygen proceeds in the cathode catalyst layer 3b. The catalyst layer 3 contains a catalyst component, a conductive catalyst carrier that supports the catalyst component, and an electrolyte. Hereinafter, a composite in which a catalyst component is supported on a catalyst carrier is also referred to as an “electrode catalyst”.
　アノード触媒層３ａに用いられる触媒成分は、水素の酸化反応に触媒作用を有するものであれば特に制限はなく公知の触媒が使用できる。また、カソード触媒層３ｂに用いられる触媒成分もまた、酸素の還元反応に触媒作用を有するものであれば特に制限はなく公知の触媒が使用できる。具体的には、白金、ルテニウム、イリジウム、ロジウム、パラジウム、オスミウム、タングステン、鉛、鉄、クロム、コバルト、ニッケル、マンガン、バナジウム、モリブデン、ガリウム、アルミニウム等の金属及びこれらの合金などから選択される。 The catalyst component used in the anode catalyst layer 3a is not particularly limited as long as it has a catalytic action in the oxidation reaction of hydrogen, and a known catalyst can be used. The catalyst component used for the cathode catalyst layer 3b is not particularly limited as long as it has a catalytic action for the oxygen reduction reaction, and a known catalyst can be used. Specifically, it is selected from metals such as platinum, ruthenium, iridium, rhodium, palladium, osmium, tungsten, lead, iron, chromium, cobalt, nickel, manganese, vanadium, molybdenum, gallium, aluminum, and alloys thereof. .
　これらのうち、触媒活性、一酸化炭素等に対する耐被毒性、耐熱性などを向上させるために、少なくとも白金を含むものが好ましく用いられる。前記合金の組成は、合金化する金属の種類にもよるが、白金の含有量を３０～９０原子％とし、白金と合金化する金属の含有量を１０～７０原子％とするのが良い。なお、合金とは、一般に金属元素に一種以上の金属元素又は非金属元素を加えたものであって、金属的性質をもっているものの総称である。合金の組織には、成分元素が別個の結晶となるいわば混合物である共晶合金、成分元素が完全に溶け合い固溶体となっているもの、成分元素が金属間化合物又は金属と非金属との化合物を形成しているものなどがあり、本願ではいずれであっても良い。この際、アノード触媒層３ａに用いられる触媒成分及びカソード触媒層３ｂに用いられる触媒成分は、上記の中から適宜選択される。本明細書では、特記しない限り、アノード触媒層用及びカソード触媒層用の触媒成分についての説明は、両者について同様の定義である。よって、一括して「触媒成分」と称する。しかしながら、アノード触媒層３ａ及びカソード触媒層３ｂの触媒成分は同一である必要はなく、上記したような所望の作用を奏するように、適宜選択される。 Among these, those containing at least platinum are preferably used in order to improve catalytic activity, poisoning resistance to carbon monoxide, heat resistance, and the like. Although the composition of the alloy depends on the type of metal to be alloyed, the content of platinum is preferably 30 to 90 atomic%, and the content of the metal to be alloyed with platinum is preferably 10 to 70 atomic%. In general, an alloy is a general term for a metal element having one or more metal elements or non-metal elements added and having metallic properties. In the alloy structure, the eutectic alloy, which is a mixture of the component elements to form separate crystals, the component elements are completely melted into a solid solution, the component element is an intermetallic compound or a compound of a metal and a nonmetal. There is what is formed, and any may be used in the present application. At this time, the catalyst component used for the anode catalyst layer 3a and the catalyst component used for the cathode catalyst layer 3b are appropriately selected from the above. In the present specification, unless otherwise specified, descriptions of the catalyst components for the anode catalyst layer and the cathode catalyst layer have the same definition for both. Therefore, they are collectively referred to as “catalyst components”. However, the catalyst components of the anode catalyst layer 3a and the cathode catalyst layer 3b do not need to be the same, and are appropriately selected so as to exhibit the desired action as described above.
　触媒成分の形状や大きさは、特に制限されず公知の触媒成分と同様の形状及び大きさが採用される。ただし、触媒成分の形状は、粒状であることが好ましい。この際、触媒粒子の平均粒子径は、好ましくは１ｎｍ～３０ｎｍである。触媒粒子の平均粒子径がこのような範囲内の値であると、電気化学反応が進行する有効電極面積に関連する触媒利用率と担持の簡便さとのバランスが適切に制御される。なお、本明細書における「触媒粒子の平均粒子径」は、Ｘ線回折における触媒成分の回折ピークの半値幅より求められる結晶子径や、透過形電子顕微鏡像より調べられる触媒成分の粒子径の平均値として測定される。 The shape and size of the catalyst component are not particularly limited, and the same shape and size as known catalyst components are employed. However, the shape of the catalyst component is preferably granular. At this time, the average particle diameter of the catalyst particles is preferably 1 nm to 30 nm. When the average particle size of the catalyst particles is within such a range, the balance between the catalyst utilization rate related to the effective electrode area where the electrochemical reaction proceeds and the ease of loading is appropriately controlled. The “average particle diameter of the catalyst particles” in the present specification is the crystallite diameter determined from the half-value width of the diffraction peak of the catalyst component in X-ray diffraction or the particle diameter of the catalyst component determined from a transmission electron microscope image. Measured as an average value.
　触媒担体は、上述した触媒成分を担持するための担体、及び触媒成分と他の部材との間での電子の授受に関与する電子伝導パスとして機能する。 The catalyst carrier functions as a carrier for supporting the above-described catalyst component and an electron conduction path involved in the transfer of electrons between the catalyst component and another member.
　触媒担体としては、触媒成分を所望の分散状態で担持させるための比表面積を有し、充分な電子伝導性を有しているものであれば良く、主成分がカーボンであることが好ましい。具体的には、カーボンブラック、活性炭、コークス、天然黒鉛、人造黒鉛などからなるカーボン粒子が挙げられる。なお、「主成分がカーボンである」とは、主成分として炭素原子を含むことをいい、炭素原子のみからなる、実質的に炭素原子からなる、の双方を含む概念である。場合によっては、燃料電池の特性を向上させるために、炭素原子以外の元素が含まれていても良い。なお、「実質的に炭素原子からなる」とは、２～３質量％程度以下の不純物の混入が許容されることを意味する。 The catalyst carrier may be any catalyst carrier as long as it has a specific surface area for supporting the catalyst component in a desired dispersed state and has sufficient electron conductivity, and the main component is preferably carbon. Specific examples include carbon particles made of carbon black, activated carbon, coke, natural graphite, artificial graphite and the like. “The main component is carbon” means that the main component contains carbon atoms, and is a concept that includes both carbon atoms and substantially carbon atoms. In some cases, elements other than carbon atoms may be included in order to improve the characteristics of the fuel cell. Incidentally, “substantially consisting of carbon atoms” means that contamination of about 2 to 3% by mass or less of impurities is allowed.
　触媒担体のＢＥＴ比表面積は、触媒成分を高分散担持させるのに充分な比表面積であれば良いが、好ましくは２０～１６００ｍ２／ｇ、より好ましくは８０～１２００ｍ２／ｇである。触媒担体の比表面積がこのような範囲内の値であると、触媒担体上での触媒成分の分散性と触媒成分の有効利用率とのバランスが適切に制御される。 The BET specific surface area of the catalyst carrier may be a specific surface area sufficient to carry the catalyst component in a highly dispersed state, but is preferably 20 to 1600 m 2 / g, more preferably 80 to 1200 m 2 / g. When the specific surface area of the catalyst support is within this range, the balance between the dispersibility of the catalyst component on the catalyst support and the effective utilization rate of the catalyst component is appropriately controlled.
　触媒担体のサイズについても特に限定されないが、担持の簡便さ、触媒利用率、触媒層の厚みを適切な範囲で制御するなどの観点からは、平均粒子径を５～２００ｎｍ程度、好ましくは１０～１００ｎｍ程度とすると良い。 The size of the catalyst carrier is not particularly limited, but from the viewpoint of easy loading, catalyst utilization, and catalyst layer thickness control within an appropriate range, the average particle size is about 5 to 200 nm, preferably 10 to 10 nm. About 100 nm is preferable.
　触媒担体に触媒成分が担持されてなる電極触媒において、触媒成分の担持量は、電極触媒の全量に対して、好ましくは１０～８０質量％、より好ましくは３０～７０質量％である。触媒成分の担持量がこのような範囲内の値であると、触媒担体上での触媒成分の分散度と触媒性能とのバランスが適切に制御される。なお、電極触媒における触媒成分の担持量は、誘導結合プラズマ発光分光法（ＩＣＰ）によって測定される。 In the electrode catalyst in which the catalyst component is supported on the catalyst carrier, the amount of the catalyst component supported is preferably 10 to 80% by mass, more preferably 30 to 70% by mass, based on the total amount of the electrode catalyst. When the supported amount of the catalyst component is within such a range, the balance between the degree of dispersion of the catalyst component on the catalyst carrier and the catalyst performance is appropriately controlled. The amount of the catalyst component supported on the electrode catalyst is measured by inductively coupled plasma emission spectroscopy (ICP).
　触媒層３には、電極触媒に加えて、イオン伝導性の高分子電解質が含まれる。当該高分子電解質は特に限定されず従来公知の知見が適宜参照される。例えば、上述した電解質膜２を構成するイオン交換樹脂が、高分子電解質として触媒層３に添加される。 The catalyst layer 3 contains an ion conductive polymer electrolyte in addition to the electrode catalyst. The said polymer electrolyte is not specifically limited, A conventionally well-known knowledge is referred suitably. For example, the ion exchange resin which comprises the electrolyte membrane 2 mentioned above is added to the catalyst layer 3 as a polymer electrolyte.
　［ガス拡散層（ＧＤＬ）］
　図１、１３に示すガス拡散層４ａ、４ｂは、金属セパレータ５ａ、５ｂのガス流路５ａａ、５ｂｂを介して供給されたガス５ａｇ、５ｂｇの、触媒層３ａ、３ｂへの拡散を促進する機能、及び電子伝導パスとしての機能を有する。 [Gas diffusion layer (GDL)]
The gas diffusion layers 4a and 4b shown in FIGS. 1 and 13 promote the diffusion of the gases 5ag and 5bg supplied through the gas flow paths 5aa and 5bb of the metal separators 5a and 5b into the catalyst layers 3a and 3b. And function as an electron conduction path.
　ガス拡散層４（４ａ、４ｂ）の基材を構成する材料は特に限定されない。例えば、炭素製の織物、紙状抄紙体、フェルト、不織布といった導電性及び多孔質性を有するシート状材料が挙げられる。ガス拡散層４の基材の厚さは、得られるガス拡散層４の特性を考慮して適宜決定すれば良いが、３０μｍ～５００μｍ程度とすれば良い。ガス拡散層４の基材の厚さがこのような範囲内の値であれば、機械的強度とガス及び水などの拡散性とのバランスが適切に制御される。 The material constituting the base material of the gas diffusion layer 4 (4a, 4b) is not particularly limited. For example, a sheet-like material having conductivity and porosity such as a carbon woven fabric, a paper-like paper body, a felt, and a non-woven fabric can be used. The thickness of the base material of the gas diffusion layer 4 may be appropriately determined in consideration of the characteristics of the obtained gas diffusion layer 4, but may be about 30 μm to 500 μm. If the thickness of the base material of the gas diffusion layer 4 is a value within such a range, the balance between the mechanical strength and the diffusibility of gas, water, and the like is appropriately controlled.
　ガス拡散層４は、撥水性をより高めてフラッディング現象などを防止することを目的として、撥水剤を含むことが好ましい。撥水剤としては、ポリテトラフルオロエチレン（ＰＴＦＥ）、ポリフッ化ビニリデン（ＰＶｄＦ）、ポリヘキサフルオロプロピレン、テトラフルオロエチレン－ヘキサフルオロプロピレン共重合体（ＦＥＰ）などのフッ素系の高分子材料、ポリプロピレン、ポリエチレンなどが挙げられる。 The gas diffusion layer 4 preferably contains a water repellent for the purpose of further improving the water repellency and preventing the flooding phenomenon. Examples of the water repellent include fluorine-based polymer materials such as polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), polyhexafluoropropylene, tetrafluoroethylene-hexafluoropropylene copolymer (FEP), polypropylene, Examples include polyethylene.
　また、撥水性をより向上させるために、ガス拡散層４は、撥水剤を含むカーボン粒子の集合体からなるカーボン粒子層を基材の触媒層側に有するものであっても良い。 In order to further improve the water repellency, the gas diffusion layer 4 may have a carbon particle layer made of an aggregate of carbon particles containing a water repellent on the catalyst layer side of the base material.
　カーボン粒子層に含まれるカーボン粒子としては、カーボンブラック、グラファイト、膨張黒鉛などの従来公知の材料が適宜採用される。なかでも、電子伝導性に優れ、比表面積が大きいことから、オイルファーネスブラック、チャネルブラック、ランプブラック、サーマルブラック、アセチレンブラックなどのカーボンブラックが好ましく用いられる。カーボン粒子の平均粒子径は、１０ｎｍ～１００ｎｍ程度とするのが良い。これにより、毛細管力による高い排水性が得られるとともに、触媒層３との接触性も向上させることが可能となる。 As the carbon particles contained in the carbon particle layer, conventionally known materials such as carbon black, graphite, and expanded graphite are appropriately employed. Of these, carbon blacks such as oil furnace black, channel black, lamp black, thermal black, and acetylene black are preferably used because of excellent electron conductivity and a large specific surface area. The average particle diameter of the carbon particles is preferably about 10 nm to 100 nm. Thereby, while being able to obtain the high drainage property by capillary force, the contact property with the catalyst layer 3 can be improved.
　カーボン粒子層に用いられる撥水剤としては、上述した撥水剤と同様のものが挙げられる。なかでも、撥水性、電極反応時の耐食性などに優れることから、フッ素系の高分子材料が好ましく用いられる。 Examples of the water repellent used for the carbon particle layer include the same water repellents as described above. Of these, fluorine-based polymer materials are preferably used because of their excellent water repellency and corrosion resistance during electrode reaction.
　カーボン粒子層におけるカーボン粒子と撥水剤との混合比は、撥水性及び電子伝導性のバランスを考慮して、質量比で９０：１０～４０：６０（カーボン粒子：撥水剤）程度とするのが良い。なお、カーボン粒子層の厚さについても、得られるガス拡散層の撥水性を考慮して適宜決定すれば良いが、好ましくは１０～１０００μｍ、より好ましくは５０～５００μｍとするのが良い。 The mixing ratio of the carbon particles to the water repellent in the carbon particle layer is about 90:10 to 40:60 (carbon particles: water repellent) in mass ratio in consideration of the balance between water repellency and electron conductivity. Is good. The thickness of the carbon particle layer may be appropriately determined in consideration of the water repellency of the obtained gas diffusion layer, but is preferably 10 to 1000 μm, more preferably 50 to 500 μm.
　［セルユニットの基本的な構成］
　図１及び１３において、単セル１は、固体高分子電解質膜２の両側に、電極触媒層３ａ及びガス拡散層４ａからなる燃料極と、電極触媒層３ｂ及びガス拡散層４ｂからなる酸素極とが、それぞれ配置されてなるＭＥＡ９を有している。さらにＭＥＡ９を、アノードセパレータ５ａ及びカソードセパレータ５ｂで挟持されてなる。また、ＭＥＡ９に供給される燃料ガス５ａｇ及び酸化剤ガス５ｂｇは、アノードセパレータ５ａ及びカソードセパレータ５ｂに、燃料ガス流路５ａａ及び酸化剤ガス流路５ｂｂなどを介して供給される。 [Basic configuration of cell unit]
1 and 13, a single cell 1 includes a fuel electrode composed of an electrode catalyst layer 3a and a gas diffusion layer 4a, an oxygen electrode composed of an electrode catalyst layer 3b and a gas diffusion layer 4b on both sides of the solid polymer electrolyte membrane 2. Have MEAs 9 arranged respectively. Further, the MEA 9 is sandwiched between the anode separator 5a and the cathode separator 5b. The fuel gas 5ag and the oxidant gas 5bg supplied to the MEA 9 are supplied to the anode separator 5a and the cathode separator 5b through the fuel gas flow path 5aa, the oxidant gas flow path 5bb, and the like.
　そして、単セル１を単独又は２以上積層したスタックを、さらに厚さ方向の両側から一対のエンドプレート、すなわち燃料極側エンドプレート７０及び酸素極側エンドプレート８０で締結する（図１４参照）。 Then, a stack of single cells 1 or two or more stacked one by one is further fastened by a pair of end plates, that is, a fuel electrode side end plate 70 and an oxygen electrode side end plate 80 from both sides in the thickness direction (see FIG. 14).
　本燃料電池は、電源として利用される。電源の用途は、例えば、定置用、携帯電話などの民生用携帯機器用、非常用、レジャーや工事用電源などの屋外用、搭載スペースが限定される自動車などの移動体用である。特に、移動体用電源は、比較的長時間の運転停止後に高い出力電圧が要求される。また、本実施形態の燃料電池を搭載してなる車両では、金属セパレータ５、集電板３０、４０等の構成部品（導電部材）を通じて薄肉化、低コスト化が図れ、燃料電池の出力密度の向上に寄与し得る。そのため、車両重量の軽減や車両コストの低減が図れる。また同じ体積の燃料電池を搭載した際に、より長い走行距離を走ることができ、また加速性能のなどの向上にもつながる。加えて、燃料電池の金属セパレータ５、集電板３０、４０等の導電部材は耐食性にも優れ、燃料電池スタック２０の耐久性の向上及び長寿命化も図れる。 This fuel cell is used as a power source. Applications of the power source include, for example, stationary devices, consumer portable devices such as mobile phones, emergency devices, outdoor devices such as leisure and construction power sources, and mobile objects such as automobiles with limited mounting space. In particular, the mobile power source is required to have a high output voltage after a relatively long time of operation stop. In addition, in a vehicle equipped with the fuel cell of this embodiment, the thickness and cost can be reduced through components (conductive members) such as the metal separator 5 and the current collector plates 30 and 40, and the output density of the fuel cell can be reduced. Can contribute to improvement. Therefore, the vehicle weight can be reduced and the vehicle cost can be reduced. In addition, when a fuel cell of the same volume is installed, the vehicle can run for a longer distance, and the acceleration performance can be improved. In addition, the conductive members such as the metal separator 5 and the current collector plates 30 and 40 of the fuel cell are excellent in corrosion resistance, and the durability of the fuel cell stack 20 can be improved and the life can be extended.
　スタック２０の両側には、集電板３０、４０、絶縁板５０、６０及びエンドプレート７０、８０が配置される。集電板３０、４０は、緻密質カーボンや銅板、アルミ板などガス不透過な導電性部材から形成される。また、スタック２０で生じた起電力を出力するための出力端子３７、４７が設けられている。絶縁板５０、６０は、ゴムや樹脂等の絶縁性部材から形成される。 Current collector plates 30 and 40, insulating plates 50 and 60, and end plates 70 and 80 are disposed on both sides of the stack 20. The current collecting plates 30 and 40 are made of a gas impermeable conductive member such as dense carbon, copper plate, or aluminum plate. Further, output terminals 37 and 47 for outputting electromotive force generated in the stack 20 are provided. The insulating plates 50 and 60 are formed from an insulating member such as rubber or resin.
　ここで、上記集電板３０、４０として、上記したカーボン等に変えて、薄肉化、低コスト化の観点から、銅板やアルミ板等を用いる場合には、本実施形態の導電部材を採用することができる。銅板やアルミ板は、ステンレスよりも薄肉軽量化に優れる反面、耐食性に乏しい。しかし中間層及び導電性炭素層を形成することにより、中間層で液滴の浸入によるアルミ板の腐食を防止しつつ、導電性炭素層の最表面で電気抵抗を低減することができる。その結果、金属製集電板３０、４０の導電性を維持したまま酸性雰囲気下に曝されても化学的安定性を維持することが出来る。つまり、図１３に示すように、金属セパレータ５との接触抵抗を増加させることなく、ピンホール等の欠陥によるイオン溶出を抑制できる集電板３０、４０を提供することができる。 Here, instead of the above-described carbon or the like as the current collecting plates 30 and 40, in the case of using a copper plate, an aluminum plate, or the like from the viewpoint of thinning and cost reduction, the conductive member of this embodiment is employed. be able to. Copper plates and aluminum plates are thinner and lighter than stainless steel, but have poor corrosion resistance. However, by forming the intermediate layer and the conductive carbon layer, it is possible to reduce the electrical resistance on the outermost surface of the conductive carbon layer while preventing the corrosion of the aluminum plate due to the ingress of droplets in the intermediate layer. As a result, the chemical stability can be maintained even if the metal current collector plates 30 and 40 are exposed to an acidic atmosphere while maintaining the conductivity. That is, as shown in FIG. 13, current collector plates 30 and 40 that can suppress ion elution due to defects such as pinholes without increasing the contact resistance with metal separator 5 can be provided.
　また、図１４に示すように、エンドプレート７０、８０は、剛性を備えた材料、例えば鋼などの金属材料から形成される。エンドプレート７０、８０は、燃料ガス導入口７１、燃料ガス排出口７２、酸化剤ガス導入口７４、酸化剤ガス排出口７５、冷却水導入口７７及び冷却水排出口７８を有する。燃料ガス導入口７１、燃料ガス排出口７２、酸化剤ガス導入口７４、酸化剤ガス排出口７５、冷却水導入口７７及び冷却水排出口７８は、燃料ガス５ａｇ、酸化剤ガス５ｂｇ及び冷却水８ｗを流通させるために、燃料ガス流路５ａａ、酸化剤ガス流路５ｂｂ及び冷却水流路８に連通している。 Further, as shown in FIG. 14, the end plates 70 and 80 are formed of a material having rigidity, for example, a metal material such as steel. The end plates 70, 80 have a fuel gas inlet 71, a fuel gas outlet 72, an oxidant gas inlet 74, an oxidant gas outlet 75, a cooling water inlet 77 and a cooling water outlet 78. The fuel gas inlet 71, the fuel gas outlet 72, the oxidant gas inlet 74, the oxidant gas outlet 75, the cooling water inlet 77 and the cooling water outlet 78 are the fuel gas 5ag, the oxidant gas 5bg and the cooling water. In order to distribute 8w, it communicates with the fuel gas channel 5aa, the oxidant gas channel 5bb and the cooling water channel 8.
　図１４に示すように、スタック２０、集電板３０、４０、絶縁板５０、６０及びエンドプレート７０、８０の四隅には、タイロッド９０が挿通される貫通孔が配置される。タイロッド９０は、その端部に形成される雄ねじにナット（図示せず）が螺合され、燃料電池スタック２０をエンドプレート７０、８０により締結する。スタック２０形成のための荷重は、燃料電池単セル１の積層方向に作用し、単セル１を押圧状態に保持する。 As shown in FIG. 14, through holes through which the tie rods 90 are inserted are arranged at the four corners of the stack 20, the current collecting plates 30, 40, the insulating plates 50, 60, and the end plates 70, 80. The tie rod 90 is screwed with a nut (not shown) to a male screw formed at an end thereof, and fastens the fuel cell stack 20 with end plates 70 and 80. The load for forming the stack 20 acts in the stacking direction of the fuel cell single cells 1 to hold the single cells 1 in a pressed state.
　図１４に示すように、タイロッド９０は、剛性を備えた材料、例えば、鋼などの金属材料から形成される。また、タイロッド９０は、燃料電池単セル２０１同士の電気的短絡を防止するため、絶縁処理された表面を有する。タイロッド９０の設置本数は、４本（四隅）に限定されない。また、タイロッド９０の締結機構は、螺合に限定されず、他の手段を適用することも可能である。 As shown in FIG. 14, the tie rod 90 is formed of a material having rigidity, for example, a metal material such as steel. Further, the tie rod 90 has an insulated surface in order to prevent an electrical short circuit between the fuel cell single cells 201. The number of tie rods 90 installed is not limited to four (four corners). Further, the fastening mechanism of the tie rod 90 is not limited to screwing, and other means can be applied.
　次に、ガスケットは、ＭＥＡ９の表面に位置するセパレータ５の外周を、取り囲むように配置されるシール部材である。そして、ガスケットは、接着層（図示せず）を介して、ＭＥＡ９の電解質膜２の外面に固定されても良い。ガスケットは、セパレータ５とＭＥＡ９と間のシール性を確保する機能を有している。なお、必要に応じて用いられる接着層は、接着性を確保することを考慮すると、ガスケットの形状に対応し、電解質膜の全周縁部に、額縁状に配置されることが好ましい。 Next, the gasket is a seal member disposed so as to surround the outer periphery of the separator 5 located on the surface of the MEA 9. The gasket may be fixed to the outer surface of the electrolyte membrane 2 of the MEA 9 via an adhesive layer (not shown). The gasket has a function of ensuring a sealing property between the separator 5 and the MEA 9. Note that the adhesive layer used as necessary preferably corresponds to the shape of the gasket and is arranged in a frame shape on the entire peripheral edge of the electrolyte membrane in consideration of securing adhesiveness.
　また、図１４に示すように、燃料電池スタック２００では、マニホールド（燃料ガス導入口７１、燃料ガス排出口７２、酸化剤ガス導入口７４、酸化剤ガス排出口７５、冷却水導入口７７及び冷却水排出口７８）の貫通孔の内壁に、上記中間層３２を形成するのが望ましい。即ち、マニホールドの貫通孔の内壁では、導電性が不要であるため、導電性炭素層を設ける必要なく、中間層（Ｃｒ層）を形成するのが望ましい。これにより、マニホールドの貫通孔の腐食を効果的に防止できる。 Further, as shown in FIG. 14, in the fuel cell stack 200, the manifold (fuel gas inlet 71, fuel gas outlet 72, oxidant gas inlet 74, oxidant gas outlet 75, cooling water inlet 77, and cooling It is desirable to form the intermediate layer 32 on the inner wall of the through hole of the water discharge port 78). That is, the inner wall of the through hole of the manifold does not require conductivity, and therefore it is desirable to form an intermediate layer (Cr layer) without providing a conductive carbon layer. Thereby, corrosion of the through hole of the manifold can be effectively prevented.
　なお、金属セパレータ５及び集電板３０、４０以外にも、導電性と耐食性を必要とする燃料電池の構成部品（導電部材）については、本実施形態の構成を採用することができる。これにより、当該導電部材、ひいては燃料電池スタックの薄肉・軽量化を図ることができ、出力密度を向上させることができる。更に、低コスト化にもつながる為、価格低減が強く求められている燃料電池車にとっても有用である。また、本実施形態の燃料電池の製造方法は、特に制限されることなく、燃料電池の分野において従来公知の知見を適宜参照することができる。 In addition to the metal separator 5 and the current collector plates 30 and 40, the configuration of the present embodiment can be adopted for the components (conductive members) of the fuel cell that require conductivity and corrosion resistance. Thereby, the said electrically-conductive member and by extension, a fuel cell stack can be reduced in thickness and weight, and an output density can be improved. Furthermore, since it leads to cost reduction, it is also useful for fuel cell vehicles that are strongly demanded for price reduction. Moreover, the manufacturing method of the fuel cell of the present embodiment is not particularly limited, and conventionally known knowledge can be appropriately referred to in the field of the fuel cell.
　燃料電池を運転する際に用いられる燃料ガスの種類としては、水素に限定されない。例えば、水素以外にも、メタノール、エタノール、１－プロパノール、２－プロパノール、１－ブタノール、２－ブタノール、３－ブタノール、ジメチルエーテル、ジエチルエーテル、エチレングリコール、ジエチレングリコールなどが用いられる。なかでも、高出力化が可能である点で、水素やメタノールが好ましく用いられる。 The type of fuel gas used when operating the fuel cell is not limited to hydrogen. For example, in addition to hydrogen, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 3-butanol, dimethyl ether, diethyl ether, ethylene glycol, diethylene glycol and the like are used. Of these, hydrogen and methanol are preferably used in that high output is possible.
　上述したセルユニット１や燃料電池スタック２００は、導電性・耐食性に優れる金属セパレータ５を用いている。したがって、当該セルユニット１や燃料電池スタック２００は出力特性・耐久性に優れ、長期間にわたって良好な発電性能を維持することができる。なお、図１に示すセルユニット１において、金属セパレータ５は、平板状の金属板に対してプレス処理を施すことで凹凸状に成形されている。ただし、このような形態のみには制限されない。例えば、平板状の金属板に対して切削処理を施すことによりガス流路５ａａ、５ｂｂや冷媒流路８を構成する凹凸形状を予め形成し、その表面に、上述した手法によって導電性炭素層３３及び中間層３２を形成することで、金属セパレータ５としても良い。 The cell unit 1 and the fuel cell stack 200 described above use the metal separator 5 having excellent conductivity and corrosion resistance. Therefore, the cell unit 1 and the fuel cell stack 200 are excellent in output characteristics and durability, and can maintain good power generation performance over a long period of time. In addition, in the cell unit 1 shown in FIG. 1, the metal separator 5 is shape | molded by the uneven | corrugated shape by performing a press process with respect to a flat metal plate. However, it is not restricted only to such a form. For example, the concave and convex shapes constituting the gas flow paths 5aa and 5bb and the refrigerant flow path 8 are formed in advance by cutting a flat metal plate, and the conductive carbon layer 33 is formed on the surface by the above-described method. In addition, the metal separator 5 may be formed by forming the intermediate layer 32.
　本実施形態のセルユニット１やこれを用いた燃料電池スタック２００は、例えば、車両に駆動用電源として搭載される。図１０は、上記燃料電池スタックを搭載した車両の概念図である。図１０に示すように、燃料電池スタック２００を燃料電池車２１０のような車両に搭載するには、例えば、燃料電池車２１０の車体中央部の座席下に搭載すれば良い。座席下に搭載すれば、車内空間及びトランクルームを広く取ることができる。場合によっては、燃料電池スタック２００を搭載する場所は、座席下に限らず、後部トランクルームの下部でもよいし、車両２１０前方のエンジンルームであっても良い。このように、上記セルユニット１や燃料電池スタック２００を搭載した車両２１０もまた、本発明の技術的範囲に包含される。上記セルユニット１や燃料電池スタック２００は出力特性・耐久性に優れる。したがって、長期間にわたって信頼性の高い燃料電池車２１０が提供される。 The cell unit 1 of this embodiment and the fuel cell stack 200 using the cell unit 1 are mounted, for example, as a drive power source in a vehicle. FIG. 10 is a conceptual diagram of a vehicle equipped with the fuel cell stack. As shown in FIG. 10, in order to mount the fuel cell stack 200 on a vehicle such as the fuel cell vehicle 210, for example, the fuel cell stack 200 may be mounted under the seat at the center of the vehicle body of the fuel cell vehicle 210. If it is mounted under the seat, the interior space and the trunk room can be widened. Depending on the case, the place where the fuel cell stack 200 is mounted is not limited to the position under the seat, but may be a lower part of the rear trunk room or an engine room in front of the vehicle 210. Thus, the vehicle 210 carrying the cell unit 1 and the fuel cell stack 200 is also included in the technical scope of the present invention. The cell unit 1 and the fuel cell stack 200 are excellent in output characteristics and durability. Therefore, a highly reliable fuel cell vehicle 210 is provided over a long period of time.
　以下、本実施形態の導電部材の効果を、実施例及び比較例を用いてさらに説明するが、本発明の技術的範囲はこれらの実施例に限定されない。 Hereinafter, the effects of the conductive member of the present embodiment will be further described using examples and comparative examples, but the technical scope of the present invention is not limited to these examples.
　［実施例I－１］
　導電部材を構成する金属基材３１の構成材料として、ステンレス板（ＳＵＳ３１６Ｌ）を準備した。ステンレス板の厚さは１００μｍである。このステンレス板を、前処理としてエタノール水溶液中で３分間超音波洗浄した。次いで、洗浄したステンレス板を真空チャンバ内に設置し、Ａｒガスによるイオンボンバード処理を行って、表面の酸化皮膜を除去した。なお、上述した前処理及びイオンボンバード処理は、いずれもステンレス板の両面に対して行った。 [Example I-1]
A stainless steel plate (SUS316L) was prepared as a constituent material of the metal base 31 constituting the conductive member. The thickness of the stainless steel plate is 100 μm. This stainless steel plate was ultrasonically cleaned in an aqueous ethanol solution for 3 minutes as a pretreatment. Next, the cleaned stainless steel plate was placed in a vacuum chamber, and ion bombardment with Ar gas was performed to remove the oxide film on the surface. The pretreatment and ion bombardment described above were both performed on both surfaces of the stainless steel plate.
　続いて、アンバランスドマグネトロンスパッタリング法により、Ｃｒをターゲットとして、ステンレス板に対して５０Ｖの大きさの負のバイアス電圧を印加しながら、ステンレス板の両面にそれぞれ０．２μｍの厚さのＣｒからなる中間層３２を形成した。 Subsequently, by applying a negative bias voltage of 50 V to the stainless steel plate with Cr as a target by using an unbalanced magnetron sputtering method, each of both surfaces of the stainless steel plate is made of 0.2 μm thick Cr. An intermediate layer 32 was formed.
　さらに、ＵＢＭＳ法により、固体グラファイトをターゲットとして、ステンレス板に対して１００Ｖの大きさの負のバイアス電圧を印加しながら、ステンレス板の両面の中間層３２の上に、それぞれ０．２μｍの厚さの導電性炭素層３３を形成した。これにより、実施例I－１の導電部材を作製した。 Furthermore, by applying a negative bias voltage of 100 V to the stainless steel plate with a solid graphite as a target by the UBMS method, the thickness of 0.2 μm on each of the intermediate layers 32 on both surfaces of the stainless steel plate. The conductive carbon layer 33 was formed. Thus, a conductive member of Example I-1 was produced.
　［実施例I－２］
　導電性炭素層３３を形成する際に印加する負のバイアス電圧の大きさ（絶対値）を１４０Ｖとしたこと以外は、上述した実施例I－１と同様の手法により、実施例I－２の導電部材を作製した。 [Example I-2]
Except that the magnitude (absolute value) of the negative bias voltage applied when forming the conductive carbon layer 33 was 140 V, the same method as in Example I-1 was used. A conductive member was produced.
　［実施例I－３］
　導電性炭素層３３を形成する際に印加する負のバイアス電圧の大きさ（絶対値）を３００Ｖとしたこと以外は、上述した実施例I－１と同様の手法により、実施例I－３の導電部材を作製した。 [Example I-3]
Except that the magnitude (absolute value) of the negative bias voltage applied when forming the conductive carbon layer 33 was set to 300 V, the method of Example I-3 was performed in the same manner as Example I-1 described above. A conductive member was produced.
　［実施例I－４］
　導電性炭素層３３を形成する際に印加する負のバイアス電圧の大きさ（絶対値）を４５０Ｖとしたこと以外は、上述した実施例I－１と同様の手法により、実施例I－４の導電部材を作製した。 [Example I-4]
Except that the magnitude (absolute value) of the negative bias voltage applied when forming the conductive carbon layer 33 was set to 450 V, the method of Example I-4 was performed in the same manner as Example I-1 described above. A conductive member was produced.
　［実施例I－５］
　金属基材３１を構成する材料をアルミニウム（アルミＡ１０５０）としたこと以外は、上述した実施例I－２と同様の手法により、実施例I－５の導電部材を作製した。 [Example I-5]
A conductive member of Example I-5 was produced by the same method as Example I-2 described above except that the material constituting the metal base 31 was aluminum (aluminum A1050).
　［実施例I－６］
　中間層３２及び導電性炭素層３３を形成する手法をアークイオンプレーティング法としたこと以外は、上述した実施例I－２と同様の手法により、実施例I－６の導電部材を作製した。 [Example I-6]
A conductive member of Example I-6 was produced by the same method as Example I-2 described above except that the method of forming the intermediate layer 32 and the conductive carbon layer 33 was the arc ion plating method.
　［実施例I－７］
　中間層３２を形成せず、ステンレス板上にＥＣＲスパッタリング法により直接導電性炭素層３３を形成したこと以外は、上述した実施例I－１と同様の手法により、実施例I－７の導電部材を作製した。 [Example I-7]
The conductive member of Example I-7 was formed in the same manner as in Example I-1 described above except that the conductive carbon layer 33 was formed directly on the stainless steel plate by ECR sputtering without forming the intermediate layer 32. Was made.
　［比較例I－１］
　中間層３２を形成せず、ステンレス板上に直接導電性炭素層３３を形成したこと、及びその形成時に負のバイアス電圧を印加しなかったこと以外は、上述した実施例I－１と同様の手法により、比較例I－１の導電部材を作製した。 [Comparative Example I-1]
The same as Example I-1 described above, except that the intermediate carbon layer 32 was not formed, the conductive carbon layer 33 was formed directly on the stainless steel plate, and no negative bias voltage was applied during the formation. A conductive member of Comparative Example I-1 was produced by the method.
　［比較例I－２］
　導電性炭素層３３の形成時に負のバイアス電圧を印加しなかったこと以外は、上述した実施例I－１と同様の手法により、比較例I－２の導電部材を作製した。 [Comparative Example I-2]
A conductive member of Comparative Example I-2 was produced by the same method as Example I-1 described above, except that a negative bias voltage was not applied when the conductive carbon layer 33 was formed.
　［比較例I－３］
　中間層３２及び導電性炭素層３３を形成する手法をプラズマ化学気相蒸着（ＣＶＤ）法としたこと以外は、上述した実施例I－１と同様の手法により、比較例I－３の導電部材を作製した。 [Comparative Example I-3]
The conductive member of Comparative Example I-3 was prepared in the same manner as in Example I-1 described above except that the method of forming the intermediate layer 32 and the conductive carbon layer 33 was a plasma chemical vapor deposition (CVD) method. Was made.
　［比較例I－４］
　中間層３２及び導電性炭素層３３を形成する手法をイオン化蒸着法としたこと以外は、上述した実施例I－１と同様の手法により、比較例I－４の導電部材を作製した。 [Comparative Example I-4]
A conductive member of Comparative Example I-4 was produced by the same method as Example I-1 described above, except that the method of forming the intermediate layer 32 and the conductive carbon layer 33 was an ionized vapor deposition method.
　［比較例I－５］
　中間層３２を形成せず、導電性炭素層３３を形成する手法を熱化学気相蒸着（ＣＶＤ）法とし、導電性炭素層３３の厚さを０．０８μｍとしたこと以外は、上述した実施例I－１と同様の手法により、比較例I－５の導電部材を作製した。なお、熱ＣＶＤを実施する際の成膜温度は８５０℃に設定した。 [Comparative Example I-5]
The above-described implementation is performed except that the method of forming the conductive carbon layer 33 without forming the intermediate layer 32 is a thermal chemical vapor deposition (CVD) method, and the thickness of the conductive carbon layer 33 is 0.08 μm. A conductive member of Comparative Example I-5 was produced in the same manner as in Example I-1. In addition, the film-forming temperature at the time of implementing thermal CVD was set to 850 degreeC.
　［実施例I－８］
　導電部材を構成する金属基材３１の構成材料として、アルミニウム板（アルミＡ１０５０）を準備した。アルミニウム板の厚さは２００μｍである。このアルミニウム板を用い、前処理としてエタノール液中で３分間超音波洗浄した後、さらに真空チャンバに該金属基材３１を設置し、Ａｒガスによるイオンボンバード処理を行い、表面の酸化皮膜を除去した。前記前処理及び前記イオンボンバード処理は、いずれも金属基材３１の両面について行った。 [Example I-8]
An aluminum plate (aluminum A1050) was prepared as a constituent material of the metal base 31 constituting the conductive member. The thickness of the aluminum plate is 200 μm. Using this aluminum plate, ultrasonic cleaning was performed in ethanol solution for 3 minutes as a pretreatment, and then the metal substrate 31 was placed in a vacuum chamber, and ion bombardment with Ar gas was performed to remove the oxide film on the surface. . Both the pretreatment and the ion bombardment treatment were performed on both surfaces of the metal substrate 31.
　次に、アンバランスドマグネトロンスパッタリング法により、Ｃｒをターゲットとして使用し、負のバイアス電圧を５０Ｖ印加しながら、金属基材３１の両面に膜厚０．１μｍのＣｒ皮膜（中間層Ａ）を形成させた。 Next, a Cr film (intermediate layer A) having a film thickness of 0.1 μm is formed on both surfaces of the metal base 31 using Cr as a target and applying a negative bias voltage of 50 V by an unbalanced magnetron sputtering method. I let you.
　次に中間層Ａ上に、金属基材３１に負のバイアス電圧を２００Ｖ印加しながら、金属基材３１の両面において、膜厚１μｍのＣｒ層を成膜した。なお、当該Ｃｒ層に中間層Ａを含め中間層３２となる。 Next, a Cr layer having a thickness of 1 μm was formed on both surfaces of the metal base 31 while applying a negative bias voltage of 200 V to the metal base 31 on the intermediate layer A. The intermediate layer 32 including the intermediate layer A is included in the Cr layer.
　さらに、この中間層３２上に、ＵＢＭＳ法により、固体グラファイトをターゲットとして使用し、アルミニウム板に対して１４０Ｖの大きさの負のバイアス電圧を印加しながら、アルミニウム板の両面のＣｒ層（中間層３２）の上に、それぞれ０．２μｍの厚さの導電性炭素層３３を成膜した。これにより、実施例I－８の導電部材を作製した。 Further, on this intermediate layer 32, a solid graphite is used as a target by the UBMS method, and a negative bias voltage having a magnitude of 140 V is applied to the aluminum plate, while Cr layers (intermediate layer) on both sides of the aluminum plate are applied. A conductive carbon layer 33 having a thickness of 0.2 μm was formed on the layer 32). Thus, a conductive member of Example I-8 was produced.
　［実施例I－９］
　導電部材を構成する金属基材３１の構成材料として、アルミニウム板（アルミＡ１０５０）を準備した。アルミニウム板の厚さは２００μｍである。このアルミニウム板を用い、前処理としてエタノール液中で３分間超音波洗浄した後、さらに真空チャンバに該金属基材３１を設置し、Ａｒガスによるイオンボンバード処理を行い、表面の酸化皮膜を除去した。前記前処理及び前記イオンボンバード処理は、いずれも金属基材３１の両面について行った。 [Example I-9]
An aluminum plate (aluminum A1050) was prepared as a constituent material of the metal base 31 constituting the conductive member. The thickness of the aluminum plate is 200 μm. Using this aluminum plate, ultrasonic cleaning was performed in ethanol solution for 3 minutes as a pretreatment, and then the metal substrate 31 was placed in a vacuum chamber, and ion bombardment with Ar gas was performed to remove the oxide film on the surface. . Both the pretreatment and the ion bombardment treatment were performed on both surfaces of the metal substrate 31.
　次に、アンバランスドマグネトロンスパッタリング法により、Ｃｒをターゲットとして使用し、負のバイアス電圧を５０Ｖ印加しながら、金属基材３１の両面に膜厚１μｍのＣｒ層を形成させた。なお、当該Ｃｒ層のみが中間層３２となる。 Next, a Cr layer having a thickness of 1 μm was formed on both surfaces of the metal substrate 31 by using unbalanced magnetron sputtering method while using Cr as a target and applying a negative bias voltage of 50V. Note that only the Cr layer becomes the intermediate layer 32.
　さらに、この中間層３２上に、ＵＢＭＳ法により、固体グラファイトをターゲットとして使用し、アルミニウム板に対して１４０Ｖの大きさの負のバイアス電圧を印加しながら、アルミニウム板の両面のＣｒ層（中間層３２）の上に、それぞれ０．２μｍの厚さの導電性炭素層３３を成膜した。これにより、実施例I－９の導電部材を作製した。 Further, on this intermediate layer 32, a solid graphite is used as a target by the UBMS method, and a negative bias voltage having a magnitude of 140 V is applied to the aluminum plate, while Cr layers (intermediate layer) on both sides of the aluminum plate are applied. A conductive carbon layer 33 having a thickness of 0.2 μm was formed on the layer 32). Thus, a conductive member of Example I-9 was produced.
　［Ｒ値の測定］
　上記の各実施例I－１～９及び各比較例I－１～５において作製した導電部材について、導電性炭素層３３のＲ値の測定を行った。具体的には、まず、顕微ラマン分光器を用いて、導電性炭素層３３のラマンスペクトルを計測した。そして、１３００～１４００ｃｍ－１ に位置するＤバンドのピーク強度（ＩＤ）と、１５００～１６００ｃｍ－１に位置するＧバンドのピーク強度（ＩＧ）とのピーク面積比（ＩＤ／ＩＧ）を算出して、Ｒ値とした。得られた結果を下記の表１に示す。 [Measurement of R value]
The conductive member produced in each of the above Examples I-1 to 9 and Comparative Examples I-1 to I-5 was measured for the R value of the conductive carbon layer 33. Specifically, first, the Raman spectrum of the conductive carbon layer 33 was measured using a microscopic Raman spectrometer. Then, 1300 ~ 1400 cm peak intensity of D-band located -1 (I D), 1500 ~ 1600cm peak intensity of G-band located -1 (I G) and the peak area ratio of the (I D / I G) Was calculated as an R value. The obtained results are shown in Table 1 below.
　表１に示すように、実施例I－１～I－９において作製した導電部材における導電性炭素層３３のＤバンドピーク強度（ＩＤ）とＧバンドピーク強度（ＩＧ）との強度比Ｒ（ＩＤ／ＩＧ）は、いずれも１．３以上であった。一方、比較例I－１～I－５において作製した導電部材における導電性炭素層のＲ値は、いずれも１．３未満であった。なお、表１では、強度比Ｒ（ＩＤ／ＩＧ）を「Ｄ／Ｇ」として表記している。以下、強度比Ｒ（ＩＤ／ＩＧ）を単に「Ｒ値」とも略記する。 As shown in Table 1, the intensity ratio R between the D band peak intensity (I D ) and the G band peak intensity (I G ) of the conductive carbon layer 33 in the conductive members produced in Examples I-1 to I-9. (I D / I G ) was 1.3 or more in all cases. On the other hand, the R values of the conductive carbon layers in the conductive members produced in Comparative Examples I-1 to I-5 were all less than 1.3. In Table 1, the intensity ratio R (I D / I G ) is expressed as “D / G”. Hereinafter, the intensity ratio R (I D / I G ) is also simply abbreviated as “R value”.
　［導電性炭素層３３における水素原子の含有量の測定］
　上記の各実施例I－１～I－９及び各比較例I－１～I－５において作製した導電部材について、弾性反跳散乱分析法（ＥＲＤＡ）により、導電性炭素層３３における水素原子の含有量を測定した。得られた結果を下記の表１に示す。 [Measurement of hydrogen atom content in conductive carbon layer 33]
With respect to the conductive members prepared in each of the above Examples I-1 to I-9 and Comparative Examples I-1 to I-5, the hydrogen atoms in the conductive carbon layer 33 were analyzed by elastic recoil scattering analysis (ERDA). The content was measured. The obtained results are shown in Table 1 below.
　［導電性炭素層３３のビッカース硬度（Ｈｖ）の測定］
　上記の各実施例I－１～I－９及び各比較例I－１～I－５において作製した導電部材について、ナノインデンテーション法により、導電性炭素層のビッカース硬度（Ｈｖ）を測定した。得られた結果を下記の表１に示す。 [Measurement of Vickers Hardness (Hv) of Conductive Carbon Layer 33]
The Vickers hardness (Hv) of the conductive carbon layer was measured by the nanoindentation method for the conductive members produced in the above Examples I-1 to I-9 and Comparative Examples I-1 to I-5. The obtained results are shown in Table 1 below.
　表１に示すように、実施例I－１～I－９において作製した導電部材における導電性炭素層３３のビッカース硬度（Ｈｖ）は、いずれも１５００Ｈｖ以下であった。 As shown in Table 1, the Vickers hardness (Hv) of the conductive carbon layer 33 in the conductive members produced in Examples I-1 to I-9 were all 1500 Hv or less.
　［接触抵抗の測定］
　上記の各実施例I－１～I－９及び各比較例I－１～I－５において作製した導電部材について、導電部材の積層方向の接触抵抗の測定を行った。具体的には、図１１に示すように、作製した導電部材（金属セパレータ５）の両側を１対のガス拡散基体（ガス拡散層４ａ、４ｂ）で挟持し、得られた積層体の両側をさらに１対の電極（触媒層３ａ、３ｂ）で挟持し、その両端に電源を接続し、電極を含む積層体全体に１ＭＰａの荷重で保持して、測定装置を構成した。この測定装置に１Ａの定電流を流し、１ＭＰａの荷重をかけた時の通電量及び電圧値から、当該積層体の接触抵抗値を算出した。 [Measurement of contact resistance]
With respect to the conductive members produced in the above Examples I-1 to I-9 and Comparative Examples I-1 to I-5, the contact resistance in the stacking direction of the conductive members was measured. Specifically, as shown in FIG. 11, both sides of the produced conductive member (metal separator 5) are sandwiched between a pair of gas diffusion bases ( gas diffusion layers 4a, 4b), and both sides of the obtained laminate are Further, the measurement apparatus was configured by sandwiching between a pair of electrodes (catalyst layers 3a, 3b), connecting a power source to both ends thereof, and holding the entire laminate including the electrodes with a load of 1 MPa. A contact resistance value of the laminate was calculated from an energization amount and a voltage value when a constant current of 1 A was passed through the measuring apparatus and a load of 1 MPa was applied.
　また、上記で接触抵抗値を測定した後、酸性水に対する浸漬試験を行い、同様に接触抵抗値を測定した。具体的には、各実施例I－１～I－９及び各比較例I－１～I－５にて成膜された各導電部材（金属セパレータ５）を３０ｍｍ×３０ｍｍのサイズに切り出し、８０℃の温度の酸性水に１００時間浸漬し、浸漬試験前後の接触抵抗値を測定した。なお、上記酸性水について、各実施例I－１～I－７及び比較例I－１～I－５はｐＨ４以下、実施例I－８～I－９は共にｐＨ６以下とした Further, after measuring the contact resistance value as described above, an immersion test in acidic water was performed, and the contact resistance value was measured in the same manner. Specifically, each conductive member (metal separator 5) formed in each of Examples I-1 to I-9 and Comparative Examples I-1 to I-5 was cut into a size of 30 mm × 30 mm, and 80 The sample was immersed in acidic water at a temperature of 100 ° C. for 100 hours, and the contact resistance values before and after the immersion test were measured. Regarding the acidic water, each of Examples I-1 to I-7 and Comparative Examples I-1 to I-5 had a pH of 4 or less, and Examples I-8 to I-9 had a pH of 6 or less.
　得られた結果を下記の表１に示す。また、表１に示す接触抵抗に関する結果に対応するグラフを図１２Ａ、１２Ｂに示す。なお、図１２Ａに示すグラフにおいて、縦軸は対数目盛りであり、当該縦軸の接触抵抗の値は相対値として示されている。 The results obtained are shown in Table 1 below. Moreover, the graph corresponding to the result regarding the contact resistance shown in Table 1 is shown to FIG. 12A and 12B. In the graph shown in FIG. 12A, the vertical axis is a logarithmic scale, and the value of the contact resistance on the vertical axis is shown as a relative value.
　表１及び図１２Ａ、１２Ｂに示すように、各実施例I－１～I－９において作製した導電部材の場合には、比較例I－１～I－５の場合とは異なり、浸漬試験後であっても、接触抵抗が極めて小さい値に抑えられる。 As shown in Table 1 and FIGS. 12A and 12B, the conductive members produced in Examples I-1 to I-9 differ from those in Comparative Examples I-1 to I-5 after the immersion test. Even so, the contact resistance can be suppressed to an extremely small value.
　更に、実施例I－８において作製した導電部材の場合には、金属基材３１に腐食しやすいアルミニウムを用いているにも関わらず、他の実施例I－５、I－９の場合と比較しても、接触抵抗が非常に小さい値に抑えられる。また、実施例I－８の導電部材は、浸漬試験後であっても、接触抵抗が非常に小さい値に抑えられる。また、金属基材３１にステンレスを用いている他の実施例I－１～I－４、I－６～I－７と遜色のない耐食性を保持することができることが確認できた。 Further, in the case of the conductive member produced in Example I-8, despite the fact that corroded aluminum is used for the metal substrate 31, it is compared with the cases of other Examples I-5 and I-9. Even so, the contact resistance can be suppressed to a very small value. In addition, the conductive member of Example I-8 has a very low contact resistance even after the immersion test. It was also confirmed that the corrosion resistance comparable to the other Examples I-1 to I-4 and I-6 to I-7 using stainless steel for the metal substrate 31 can be maintained.
　［Ａｌ溶出の測定］
　上記の実施例I－８～I－９において作製した導電部材について、上記接触抵抗の測定の際使用した浸漬試験後の酸溶液をＩＣＰ質量分析（ＩＣＰ－ＭＳ）により、Ａｌの定量分析を行った。 [Measurement of Al elution]
For the conductive members prepared in Examples I-8 to I-9 above, the acid solution after the immersion test used in the measurement of the contact resistance was subjected to quantitative analysis of Al by ICP mass spectrometry (ICP-MS). It was.
　得られた結果を下記の表２に示す。実施例I－８の導電部材は、金属基材３１に腐食しやすいアルミニウムを用いているにも関わらず、同じアルミニウムを用いた実施例I－９の導電部材と比較しても、アルミニウムの防食効果を高めることができる。具体的には、実施例I－８の導電部材は、上記浸漬試験後であっても、Ａｌの溶出量が５００ｐｐｂと、実施例I－９の導電部材のＡｌの溶出量１５００ｐｐｂと比較して極めて小さい値に抑えられる。このことから、実施例I－８のように導電性炭素層３３と金属基材３１との間に中間層３２を設け、さらに最表面に前記突起状粒子３３ａが存在する場合には、優れた導電性を十分に確保しつつ接触抵抗の増加を抑制でき、さらに金属基材３１の防食効果を高めることができることが確認できた。 The results obtained are shown in Table 2 below. Although the conductive member of Example I-8 uses aluminum that is easily corroded for the metal base material 31, it is compared with the conductive member of Example I-9 that uses the same aluminum. The effect can be enhanced. Specifically, the conductive member of Example I-8 has an Al elution amount of 500 ppb even after the above immersion test, compared with the Al elution amount of 1500 ppb of the conductive member of Example I-9. It can be suppressed to an extremely small value. From this, when the intermediate layer 32 is provided between the conductive carbon layer 33 and the metal substrate 31 as in Example I-8 and the protruding particles 33a are present on the outermost surface, it is excellent. It has been confirmed that the increase in contact resistance can be suppressed while sufficiently ensuring the electrical conductivity, and the anticorrosion effect of the metal substrate 31 can be further enhanced.
　次に、実施例I－８と実施例I－９で得られた成膜の、Ｃｒ層（柱状中間層３２）と導電性炭素層３３（ＤＬＣ層）の境目の違いがわかる図面を対比する。まず、図１５ａ及び図１５ｂは、実施例I－９及び実施例I－８の表面を観察したＳＥＭ写真である。これにより、実施例I－９と実施例I－８とで、導電部材の最表面に突起状粒子３３ａが存在の有無が容易に確認できるし、突起状粒子３３ａが１００μｍ２当たりに少なくとも３０個以上存在しているか否かも容易に確認できる。 Next, the drawings showing the difference between the boundary between the Cr layer (columnar intermediate layer 32) and the conductive carbon layer 33 (DLC layer) in the film formation obtained in Example I-8 and Example I-9 are compared. . First, FIGS. 15a and 15b are SEM photographs observing the surfaces of Example I-9 and Example I-8. Thus, in Example I-9 and Example I-8, it can be easily confirmed whether or not the protruding particles 33a are present on the outermost surface of the conductive member, and at least 30 protruding particles 33a per 100 μm 2. Whether or not it exists can be easily confirmed.
　次に、図１６ａ及び図１６ｂは、図１５ａ及び図１５ｂのＳＥＭ写真を拡大したものである。これにより、実施例I－９と実施例I－８とで、導電部材の最表面に突起状粒子３３ａが存在の有無が容易に確認できるほか、最表面での２００～５００ｎｍの径を持つ突起状粒子３３ａと、５０～１００ｎｍの径の微小粒子３３ｂが混在している様子やそれぞれの粒子の大きさも確認できる。 Next, FIGS. 16a and 16b are enlarged views of the SEM photographs of FIGS. 15a and 15b. Thus, in Example I-9 and Example I-8, the presence or absence of the protruding particles 33a can be easily confirmed on the outermost surface of the conductive member, and the protrusion having a diameter of 200 to 500 nm on the outermost surface can be confirmed. It is also possible to confirm the appearance of the mixed particles 33a and the fine particles 33b having a diameter of 50 to 100 nm and the size of each particle.
　次に、図１７ａ及び図１７ｂは、実施例I－９及び実施例I－８の断面を観察したＴＥＭ写真である。また、図１８ａ、図１８ｂは、実施例I－９及び実施例I－８の断面を観察したＳＥＭ写真である。これにより、実施例I－９と実施例I－８とで、中間層３２の断面における柱状結晶の太さを測定でき、この中間層３２の断面における柱状結晶の太さの平均値が、２００ｎｍ～５００ｎｍの範囲内であるか否かも確認できる。さらに、周辺部に対する突起状粒子３３ａの高さを測定でき、この高さがその周辺部に対して１００ｎｍ～５００ｎｍの範囲で突起していることも確認できる。加えて、Ｃｒ中間層３２の膜厚を測定でき、その膜厚が０．０２μｍ～５μｍの範囲であることも容易に確認できる。また最表層における２００ｎｍ～５００ｎｍの太さを持つ柱状結晶が容易に観察でき、その太さを持つ結晶が最表層から金属基材３１方向に対して、中間層３２膜厚全体の何％であるかも測定できる。 Next, FIGS. 17a and 17b are TEM photographs of the cross sections of Example I-9 and Example I-8. FIGS. 18a and 18b are SEM photographs of the cross sections of Example I-9 and Example I-8. Thereby, in Example I-9 and Example I-8, the thickness of the columnar crystal in the cross section of the intermediate layer 32 can be measured, and the average value of the thickness of the columnar crystal in the cross section of the intermediate layer 32 is 200 nm. It can also be confirmed whether it is in the range of ~ 500 nm. Furthermore, the height of the protruding particles 33a with respect to the peripheral portion can be measured, and it can be confirmed that the height protrudes in the range of 100 nm to 500 nm with respect to the peripheral portion. In addition, the film thickness of the Cr intermediate layer 32 can be measured, and it can be easily confirmed that the film thickness is in the range of 0.02 μm to 5 μm. Further, a columnar crystal having a thickness of 200 nm to 500 nm in the outermost layer can be easily observed, and the crystal having the thickness is what percentage of the entire thickness of the intermediate layer 32 with respect to the direction of the metal substrate 31 from the outermost layer. It can also be measured.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
　注）表１中の成膜方法において、ＵＢＭ１）は「ＵＢＭスパッタリング」の略記であり、ＥＣＲ３）は「ＥＣＲスパッタリング」の略記であり、イオン２）は「イオンプレーティング」の略記であり、プラズマ４）は「プラズマＣＶＤ」の略記である。 Note) In the film forming method in Table 1, UBM 1) is an abbreviation for “UBM sputtering”, ECR 3) is an abbreviation for “ECR sputtering”, and ion 2) is an abbreviation for “ion plating”. , Plasma 4) is an abbreviation for “plasma CVD”.
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
　注）表中の「柱状太さ」は、中間層３２の断面における柱状結晶の柱の太さの平均値をいう。「突起状粒子径」は、最表面において２００～５００ｎｍの径を持つもの（径が２００～５００ｎｍの範囲内の平均値）をいう。「突起状粒子３３ａの数」は、最表面において２００～５００ｎｍの径を持つものの個数である。尚、表中の「突起状粒子径」が「－」とは、測定対象物である最表面において２００～５００ｎｍの径を持つものがないことを意味する。「突起状粒子３３ａの数」が「－」とは、測定対象物である最表面において２００～５００ｎｍの径を持つものの個数が０個という意味である。よって、「突起高さ」が「－」とは、測定対象物である突起状粒子３３ａの高さ（平均値）をいい、ここでは測定対象物である突起状粒子３３ａが０個であるため、その高さも測定不能という意味である。 Note) “Columnar thickness” in the table refers to the average value of the columnar crystal column thicknesses in the cross section of the intermediate layer 32. “Protruded particle diameter” refers to a particle having a diameter of 200 to 500 nm on the outermost surface (an average value within a range of 200 to 500 nm in diameter). The “number of protruding particles 33a” is the number of particles having a diameter of 200 to 500 nm on the outermost surface. In the table, “-” in the “protruding particle diameter” means that there is no particle having a diameter of 200 to 500 nm on the outermost surface as the measurement object. “−” As the “number of protruding particles 33a” means that the number of particles having a diameter of 200 to 500 nm on the outermost surface as the measurement object is zero. Therefore, the “projection height” of “−” means the height (average value) of the projection-like particles 33a that are the measurement object, and here, the number of the projection-like particles 33a that are the measurement object is zero. This means that its height cannot be measured.
［第二実施形態］
　次に、本発明の第二実施形態に係る導電部材及びその製造方法について、図面に基づき詳細に説明する。なお、第一実施形態と同一構成には同一符号を付し、重複する説明は省略する。 [Second Embodiment]
Next, the conductive member and the manufacturing method thereof according to the second embodiment of the present invention will be described in detail with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same structure as 1st embodiment, and the overlapping description is abbreviate | omitted.
　本実施形態の導電部材（導電構造体）は、金属基材と、前記金属基材上に形成される緻密バリア層と、前記緻密バリア層上に形成される中間層と、前記中間層上に形成される導電性薄膜層と、を有する。さらに、前記緻密バリア層は、中間層に比べて低い結晶配向性を有する。 The conductive member (conductive structure) of the present embodiment includes a metal base, a dense barrier layer formed on the metal base, an intermediate layer formed on the dense barrier layer, and the intermediate layer. And a conductive thin film layer to be formed. Furthermore, the dense barrier layer has a lower crystal orientation than the intermediate layer.
　本実施形態は、金属基材と中間層との間に、結晶配向性の低い緻密バリア層を配置することを特徴とする。これにより、電極側で生成した水は、導電性薄膜層を通過する可能性があるものの、結晶配向性の低い緻密バリア層では殆ど通過しない。このため、緻密バリア層を超えて通過する水分子は殆ど存在しない、即ち、金属基材は水に曝される危険性が殆どない。このため、本実施形態の導電部材は、長期間かつ電位にさらされた状態であっても、水による腐食を殆ど受けない。そして、本実施形態の導電部材をセパレータとして使用する燃料電池は、金属セパレータの優れた導電性を十分に確保しつつ、優れた耐久性を発揮できる。 This embodiment is characterized in that a dense barrier layer with low crystal orientation is disposed between the metal substrate and the intermediate layer. As a result, water generated on the electrode side may pass through the conductive thin film layer, but hardly passes through the dense barrier layer having low crystal orientation. For this reason, there are almost no water molecules passing through the dense barrier layer, that is, the metal substrate has almost no risk of being exposed to water. For this reason, the conductive member of this embodiment is hardly corroded by water even when it is exposed to a potential for a long time. And the fuel cell which uses the electrically-conductive member of this embodiment as a separator can exhibit the outstanding durability, fully ensuring the outstanding electroconductivity of a metal separator.
　本実施形態に係る固体高分子形燃料電池（ＰＥＦＣ）も第一実施形態に係るＰＥＦＣと同様の基本構成を有する。具体的には、図１に示すように、ＰＥＦＣは、固体高分子電解質膜２と、これを挟持する一対の触媒層（アノード触媒層３ａ及びカソード触媒層３ｂ）とを有する。そして、固体高分子電解質膜２と触媒層３（３ａ、３ｂ）との積層体はさらに、一対のガス拡散層４（アノードガス拡散層４ａ及びカソードガス拡散層４ｂ）により挟持されている。このように、固体高分子電解質膜２、一対の触媒層３（３ａ、３ｂ）及び一対のガス拡散層４（４ａ、４ｂ）は、積層された状態で膜電極接合体９を構成する。ＭＥＡ９はさらに、一対のセパレータ５（アノードセパレータ５ａ及びカソードセパレータ５ｂ）により挟持されている。 The polymer electrolyte fuel cell (PEFC) according to this embodiment also has the same basic configuration as the PEFC according to the first embodiment. Specifically, as shown in FIG. 1, the PEFC has a solid polymer electrolyte membrane 2 and a pair of catalyst layers (an anode catalyst layer 3a and a cathode catalyst layer 3b) that sandwich the membrane. The laminate of the solid polymer electrolyte membrane 2 and the catalyst layer 3 (3a, 3b) is further sandwiched between a pair of gas diffusion layers 4 (anode gas diffusion layer 4a and cathode gas diffusion layer 4b). Thus, the solid polymer electrolyte membrane 2, the pair of catalyst layers 3 (3a, 3b), and the pair of gas diffusion layers 4 (4a, 4b) constitute a membrane electrode assembly 9 in a stacked state. The MEA 9 is further sandwiched between a pair of separators 5 (an anode separator 5a and a cathode separator 5b).
　図２１は、本実施形態の導電部材たるセパレータ５Ａの構成を示す断面図である。本実施形態において、セパレータ５Ａは、金属基材１５２と、緻密バリア層１５３と、中間層１５４と、導電性薄膜層１５５とを有する。なお、ＰＥＦＣにおいて、セパレータ５Ａは、導電性薄膜層１５５がＭＥＡ９側に位置するように配置される。以下、本実施形態のセパレータ５Ａの各構成要素について詳述する。 FIG. 21 is a cross-sectional view showing a configuration of a separator 5A that is a conductive member of the present embodiment. In the present embodiment, the separator 5 </ b> A includes a metal substrate 152, a dense barrier layer 153, an intermediate layer 154, and a conductive thin film layer 155. In the PEFC, the separator 5A is arranged so that the conductive thin film layer 155 is located on the MEA 9 side. Hereinafter, each component of separator 5A of this embodiment is explained in full detail.
　［金属基材］
　金属基材１５２は、セパレータ５Ａを構成する導電部材の主層であり、導電性及び機械的強度の確保に寄与する。そして、本実施形態に係る金属基材１５２は、第一実施形態の金属基材３１と同様のものを使用することができる。 [Metal base material]
The metal base material 152 is a main layer of a conductive member that constitutes the separator 5A, and contributes to ensuring conductivity and mechanical strength. And the metal base material 152 which concerns on this embodiment can use the thing similar to the metal base material 31 of 1st embodiment.
　［緻密バリア層］
　緻密バリア層１５３は、金属基材１５２上に配置される。この層の存在によって、電極で生成した水が金属基材１５２側に入り込むことを抑制又は防止できる。ゆえに、緻密バリア層１５３の配置により、セパレータ５Ａを構成する導電部材は、導電性を確保しつつ、金属基材１５２、中間層１５４及び導電性薄膜層１５５のみを有する場合に比べて、耐食性を向上させることができる。 [Dense barrier layer]
The dense barrier layer 153 is disposed on the metal substrate 152. By the presence of this layer, it is possible to suppress or prevent water generated by the electrode from entering the metal substrate 152 side. Therefore, the arrangement of the dense barrier layer 153 ensures that the conductive member constituting the separator 5A has higher corrosion resistance than the case where only the metal substrate 152, the intermediate layer 154, and the conductive thin film layer 155 are provided while ensuring conductivity. Can be improved.
　このように結晶配向性の低い緻密バリア層を、金属基材と中間層との間に配置することにより、電極側で生成した水は、導電性薄膜層１５５は容易に通過するものの、緻密バリア層は殆ど通過しない。このため、中間層１５４や金属基材１５２までには、水が殆ど到達しないため、導電部材の腐食を有効に抑制できる。 By disposing the dense barrier layer having a low crystal orientation in this manner between the metal substrate and the intermediate layer, the water generated on the electrode side can easily pass through the conductive thin film layer 155, but the dense barrier layer. The layer hardly passes. For this reason, since water hardly reaches the intermediate layer 154 and the metal base material 152, corrosion of the conductive member can be effectively suppressed.
　本明細書において、「緻密バリア層」とは、水分子や溶出イオンが通過しない程度に緻密である層を意味し、具体的には、空隙率が１０％以下、より好ましくは７％以下である層を意味する。なお、緻密バリア層の空隙率の下限は、水分子が通過しない程度であれば特に制限されない。具体的には、緻密バリア層の空隙率の下限は、０．５％程度、より好ましくは０．７％である。ここで、「空隙率」は、層の表面及び断面をＳＥＭにより画像解析を行い、緻密バリア層を構成する金属、半金属、金属の炭化物又は金属の窒化物が占める面積率（％）を測定することによって求められる。 In the present specification, the “dense barrier layer” means a layer that is so dense that water molecules and eluted ions do not pass through. Specifically, the porosity is 10% or less, more preferably 7% or less. It means a certain layer. The lower limit of the porosity of the dense barrier layer is not particularly limited as long as water molecules do not pass therethrough. Specifically, the lower limit of the porosity of the dense barrier layer is about 0.5%, more preferably 0.7%. Here, “porosity” measures the area ratio (%) of the metal, metalloid, metal carbide or metal nitride constituting the dense barrier layer by image analysis of the surface and cross section of the layer with SEM. It is required by doing.
　本実施形態において、緻密バリア層は、中間層に比べて低い結晶配向性を有することが好ましい。このような構造をとることによって、緻密バリア層は電極側で生成した水分子を通しにくい構造となる。ここで、「結晶配向性」とは、多結晶である構造物中での結晶軸の配向具合を指す。このため、「結晶配向性が高い」とは、多結晶である構造物中で各結晶軸が同じような方向に（平行して）存在することを意味する。逆に、「結晶配向性が低い」とは、多結晶である構造物中で各結晶軸が様々な方向で存在することを意味する。また、このような結晶配向性の程度（結晶配向度）は、一般には実質的に配向性がないと考えられる、粉末Ｘ線回折などによって標準データとされたＪＣＰＤＳ（ＡＳＴＭ）データを指標として判断することができる。例えば、「結晶配向度（％）」は、ＷＡＸＤ測定により、（１２１）面に関するデバイリングの強度分布のピーク強度から求められる。 In this embodiment, the dense barrier layer preferably has a lower crystal orientation than the intermediate layer. By adopting such a structure, the dense barrier layer has a structure in which water molecules generated on the electrode side are difficult to pass through. Here, “crystal orientation” refers to the degree of orientation of crystal axes in a polycrystalline structure. Therefore, “high crystal orientation” means that each crystal axis exists in the same direction (in parallel) in a polycrystalline structure. On the other hand, “low crystal orientation” means that each crystal axis exists in various directions in a polycrystalline structure. In addition, the degree of crystal orientation (crystal orientation) is determined using JCPDS (ASTM) data, which is considered to be standard data by powder X-ray diffraction, which is generally considered to have substantially no orientation, as an index. can do. For example, “degree of crystal orientation (%)” is obtained from the peak intensity of the Debye intensity distribution on the (121) plane by WAXD measurement.
　中間層に比べて低い結晶配向性となるように緻密バリア層は、緻密バリア層の平均結晶子径や形成方法を適宜選択することによって、形成することができる。具体的には、緻密バリア層の平均結晶子径を、中間層の平均結晶子径に比べて小さくすることによって、上記緻密バリア層が形成できる。そして、中間層の平均結晶子径［Ｄ１（ｎｍ）］に対する前記緻密バリア層の平均結晶子径［Ｄ２（ｎｍ）］の比（Ｄ２／Ｄ１）が、０．１以上１未満であることが好ましく、０．１～０．５であることがより好ましい。このような範囲であれば、水分子が金属基材に実質的に到達しない程度にまで、緻密バリア層の結晶配向性を低くすることができる。また、各層の平均結晶子径もまた、上記大小関係を満たす限り特に制限されない。好ましくは、緻密バリア層の平均結晶子径［Ｄ２（ｎｍ）］は、１０ｎｍ以上３０ｎｍ未満、より好ましくは１０ｎｍ～２０ｎｍである。また、中間層の平均結晶子径［Ｄ１（ｎｍ）］は、好ましくは３０ｎｍ～１００ｎｍ、より好ましくは３０ｎｍ～５０ｎｍである。ここで、「結晶子径」とは、Ｘ線回折法におけるＳｃｈｅｒｒｅの方法によって算出される結晶子のサイズを意味する。 The dense barrier layer can be formed by appropriately selecting the average crystallite size and the forming method of the dense barrier layer so that the crystal orientation is lower than that of the intermediate layer. Specifically, the dense barrier layer can be formed by making the average crystallite size of the dense barrier layer smaller than the average crystallite size of the intermediate layer. The ratio (D 2 / D 1 ) of the average crystallite diameter [D 2 (nm)] of the dense barrier layer to the average crystallite diameter [D 1 (nm)] of the intermediate layer is 0.1 or more and less than 1. Preferably, it is more preferably 0.1 to 0.5. Within such a range, the crystal orientation of the dense barrier layer can be lowered to the extent that water molecules do not substantially reach the metal substrate. Moreover, the average crystallite diameter of each layer is not particularly limited as long as the above-described size relationship is satisfied. The average crystallite diameter [D 2 (nm)] of the dense barrier layer is preferably 10 nm or more and less than 30 nm, more preferably 10 nm to 20 nm. The average crystallite diameter [D 1 (nm)] of the intermediate layer is preferably 30 nm to 100 nm, and more preferably 30 nm to 50 nm. Here, the “crystallite diameter” means the crystallite size calculated by the Scherre method in the X-ray diffraction method.
　本実施形態において、緻密バリア層を構成する材料としては、周期律表の第４族の金属（Ｔｉ、Ｚｒ、Ｈｆ）、第５族の金属（Ｖ、Ｎｂ、Ｔａ）、第６族の金属（Ｃｒ、Ｍｏ、Ｗ）などの金属；Ｓｉ及びＢ等の半金属；上記金属の合金、炭化物及び窒化物などが挙げられる。これらのうち、クロム（Ｃｒ）、タングステン（Ｗ）、チタン（Ｔｉ）、モリブデン（Ｍｏ）、ニオブ（Ｎｂ）もしくはハフニウム（Ｈｆ）といったイオン溶出の少ない金属、又はこれらの窒化物、炭化物もしくは炭窒化物が好ましく用いられる。より好ましくは、ＣｒもしくはＴｉ、又はこれらの炭化物もしくは窒化物が用いられる。特に、上述したイオン溶出の少ない金属又はその炭化物もしくは窒化物を用いた場合、セパレータの耐食性を有意に向上させることができる。なお、上記緻密バリア層を構成する材料は単独で使用されてもあるいは二種以上の混合物の形態で使用されても良い。 In the present embodiment, the material constituting the dense barrier layer includes Group 4 metals (Ti, Zr, Hf), Group 5 metals (V, Nb, Ta), and Group 6 metals in the periodic table. Metals such as (Cr, Mo, W); metalloids such as Si and B; alloys, carbides and nitrides of the above metals. Among these, metals with low ion elution such as chromium (Cr), tungsten (W), titanium (Ti), molybdenum (Mo), niobium (Nb) or hafnium (Hf), or nitrides, carbides or carbonitrides thereof. The product is preferably used. More preferably, Cr or Ti, or a carbide or nitride thereof is used. In particular, when the above-described metal with little ion elution or a carbide or nitride thereof is used, the corrosion resistance of the separator can be significantly improved. In addition, the material which comprises the said dense barrier layer may be used independently, or may be used with the form of 2 or more types of mixtures.
　ここで、緻密バリア層を構成する材料は、下記に詳述する中間層を構成する材料（金属、金属の炭化物又は金属の窒化物）の熱膨張率と同等又はそれ以上であることが好ましい。一般的に、導電性薄膜層は熱膨張しにくく、金属基材は熱膨張しやすい。このため、上記したような熱膨張率となるように、緻密バリア層及び中間層を構成する材料を選択することにより、金属基材、緻密バリア層、中間層及び導電性薄膜層の熱による膨張収縮の差を抑制して、各層の剥離などを防止できる。また、このような場合には、中間層と緻密バリア層との密着性を向上することもできる。 Here, the material constituting the dense barrier layer is preferably equal to or higher than the thermal expansion coefficient of the material (metal, metal carbide or metal nitride) constituting the intermediate layer described in detail below. In general, the conductive thin film layer is less likely to thermally expand, and the metal substrate is likely to thermally expand. For this reason, by selecting the material constituting the dense barrier layer and the intermediate layer so as to have the above-described thermal expansion coefficient, the metal substrate, the dense barrier layer, the intermediate layer, and the conductive thin film layer are expanded by heat. By suppressing the difference in shrinkage, peeling of each layer can be prevented. In such a case, the adhesion between the intermediate layer and the dense barrier layer can also be improved.
　また、緻密バリア層を構成する材料は、下記に詳述する中間層を構成する材料と同等程度に金属的に貴である、あるいは上記中間層の材料に比べて金属的に貴であることが好ましい。これにより、緻密バリア層と中間層とで電位差が生じにくく、金属基材をより有効に保護して、導電部材の耐食性を向上できる。 Further, the material constituting the dense barrier layer should be metallicly noble to the same extent as the material constituting the intermediate layer described in detail below, or metallic noble compared to the material of the intermediate layer. preferable. Thereby, a potential difference is hardly generated between the dense barrier layer and the intermediate layer, the metal base material is more effectively protected, and the corrosion resistance of the conductive member can be improved.
　緻密バリア層１５３の厚さは、特に制限されない。ただし、セパレータ５Ａをより薄膜化することにより、燃料電池スタックのサイズをできるだけ小さくするという観点からは、緻密バリア層１５３の厚さは、好ましくは０．０１μｍ～１０μｍであり、より好ましくは０．０５μｍ～５μｍであり、さらに好ましくは０．１μｍ～２μｍである。緻密バリア層１５３の厚さが０．０１μｍ以上であれば、均一な層が形成され、金属基材の耐食性を効果的に向上させることが可能となる。一方、緻密バリア層１５３の厚さが１０μｍ以下であれば、緻密バリア層の膜応力の上昇が抑えられ、中間層や金属基材に対する皮膜追従性の低下やこれに伴う剥離・クラックの発生を防止することができる。 The thickness of the dense barrier layer 153 is not particularly limited. However, from the viewpoint of reducing the size of the fuel cell stack as much as possible by making the separator 5A thinner, the thickness of the dense barrier layer 153 is preferably 0.01 μm to 10 μm, and more preferably 0. The thickness is from 05 μm to 5 μm, more preferably from 0.1 μm to 2 μm. If the thickness of the dense barrier layer 153 is 0.01 μm or more, a uniform layer is formed, and the corrosion resistance of the metal substrate can be effectively improved. On the other hand, if the thickness of the dense barrier layer 153 is 10 μm or less, an increase in the film stress of the dense barrier layer can be suppressed, resulting in a decrease in film followability to the intermediate layer and the metal substrate, and the occurrence of peeling / cracking associated therewith. Can be prevented.
　また、本実施形態においては、金属基材１５２のすべてが緻密バリア層１５３により被覆されていることが好ましい。換言すれば、本実施形態では、緻密バリア層１５３により金属基材１５２が被覆された面積の割合（被覆率）は１００％であることが好ましい。ただし、このような形態のみには限定されず、被覆率は１００％未満であっても良い。緻密バリア層１５３による金属基材１５２の被覆率は、好ましくは６０％以上であり、より好ましくは８０～１００％であり、さらに好ましくは９０～１００％であり、最も好ましくは１００％である。このような構成とすることにより、緻密バリア層１５３により被覆されていない金属基材１５２の露出部への水分子の浸入を有効に防止して、金属基材の導電性・耐食性の低下が効果的に抑制できる。なお、上記被覆率は、導電部材（セパレータ５Ａ）を積層方向から見た場合に緻密バリア層１５３と重複する金属基材１５２の面積の割合を意味するものとする。 In the present embodiment, it is preferable that all of the metal base material 152 is covered with the dense barrier layer 153. In other words, in this embodiment, it is preferable that the ratio (coverage) of the area where the metal base material 152 is covered with the dense barrier layer 153 is 100%. However, it is not limited only to such a form, A coverage may be less than 100%. The coverage of the metal substrate 152 by the dense barrier layer 153 is preferably 60% or more, more preferably 80 to 100%, still more preferably 90 to 100%, and most preferably 100%. By adopting such a configuration, it is possible to effectively prevent water molecules from entering the exposed portion of the metal substrate 152 that is not covered with the dense barrier layer 153, and to reduce the conductivity and corrosion resistance of the metal substrate. Can be suppressed. In addition, the said coverage shall mean the ratio of the area of the metal base material 152 which overlaps with the precise | minute barrier layer 153 when a conductive member (separator 5A) is seen from a lamination direction.
　［中間層］
　中間層１５４は、緻密バリア層１５３上に配置される。ここで、中間層１５４は、緻密バリア層１５３と導電性薄膜層１５５との密着性を向上させるという機能や、金属基材１５２からのイオンの溶出を防止するという機能を有する。特に、中間層１５４の設置による作用効果は、緻密バリア層１５３が上記金属等から構成される場合に顕著に発現する。また、下記に詳述するが、導電性薄膜層１５５が導電性炭素を含みかつラマン散乱分光分析により測定されたＤバンドピーク強度（ＩＤ）とＧバンドピーク強度（ＩＧ）との強度比Ｒ（ＩＤ／ＩＧ）が大きい導電性炭素層である場合、例えばＲ値が２．０を超える場合には、中間層１５４を設けることにより導電性薄膜層１５５との密着性効果が顕著に発現する。 [Middle layer]
The intermediate layer 154 is disposed on the dense barrier layer 153. Here, the intermediate layer 154 has a function of improving the adhesion between the dense barrier layer 153 and the conductive thin film layer 155 and a function of preventing elution of ions from the metal substrate 152. In particular, the function and effect obtained by installing the intermediate layer 154 is remarkably exhibited when the dense barrier layer 153 is made of the above-described metal or the like. In addition, as will be described in detail below, the intensity ratio between the D band peak intensity (I D ) and the G band peak intensity (I G ) measured by Raman scattering spectroscopic analysis in which the conductive thin film layer 155 contains conductive carbon. When the conductive carbon layer has a large R (I D / I G ), for example, when the R value exceeds 2.0, the adhesive effect with the conductive thin film layer 155 is remarkable by providing the intermediate layer 154. Expressed in
　中間層１５４を構成する材料としては、上記密着性を付与するものであれば特に制限はないが、第一実施形態の中間層３２と同様の材料を使用することができる。また、中間層１５４の厚さは特に制限されないが、第一実施形態の中間層３２と同様の厚さとすることができる。さらに、中間層１５４の構造も特に制限されないが、第一実施形態の中間層３２と同様の柱状構造とすることができる。 The material constituting the intermediate layer 154 is not particularly limited as long as it provides the above-mentioned adhesion, but the same material as the intermediate layer 32 of the first embodiment can be used. The thickness of the intermediate layer 154 is not particularly limited, but can be the same thickness as the intermediate layer 32 of the first embodiment. Further, the structure of the intermediate layer 154 is not particularly limited, but can be a columnar structure similar to the intermediate layer 32 of the first embodiment.
　上述したように、中間層１５４を構成する材料の熱膨張率が、緻密バリア層１５３を構成する材料の熱膨張率以下であると、中間層と緻密バリア層との密着性などを向上することができる。ただし、そのような形態では中間層１５４と導電性薄膜層１５５との密着性が低下する場合がある。同様に、中間層１５４の熱膨張率が導電性薄膜層１５５の熱膨張率と同等又は以下であると、中間層１５４と導電性薄膜層１５５との密着性が低下する場合がある。これらを考慮して、金属基材を構成する材料の熱膨張率（αｓｕｂ）、緻密バリア層を構成する材料の熱膨張率（αｄｅｎ）、中間層を構成する材料の熱膨張率（αｍｉｄ）、及び導電性薄膜層を構成する材料の熱膨張率を（αｃ）は、下記関係を満足することが好ましい。 As described above, when the thermal expansion coefficient of the material constituting the intermediate layer 154 is equal to or lower than the thermal expansion coefficient of the material constituting the dense barrier layer 153, adhesion between the intermediate layer and the dense barrier layer is improved. Can do. However, in such a form, the adhesion between the intermediate layer 154 and the conductive thin film layer 155 may be reduced. Similarly, if the thermal expansion coefficient of the intermediate layer 154 is equal to or less than the thermal expansion coefficient of the conductive thin film layer 155, the adhesion between the intermediate layer 154 and the conductive thin film layer 155 may decrease. Considering these, the coefficient of thermal expansion (α sub ) of the material constituting the metal substrate, the coefficient of thermal expansion (α den ) of the material constituting the dense barrier layer, and the coefficient of thermal expansion (α of the material constituting the intermediate layer) mid ) and the coefficient of thermal expansion of the material constituting the conductive thin film layer (α c ) preferably satisfy the following relationship.
［数３］
αｓｕｂ ≧ αｄｅｎ ≧ αｍｉｄ ≧ αｃ [Equation 3]
α sub ≧ α den ≧ α mid ≧ α c
　［導電性薄膜層］
　導電性薄膜層１５５は、中間層１５４上に配置される。導電性薄膜層１５５としては、金属薄膜層及び炭素から形成された導電性炭素層などが挙げられる。このうち、金属薄膜層を構成する材料としては、銅（Ｃｕ）、金（Ａｕ）、銀（Ａｇ）、白金（Ｐｔ）、パラジウム（Ｐｄ）などが挙げられる。また、導電性炭素層は、導電性炭素を含む層である。これらのうち、導電性炭素層が好ましい。導電性炭素層の存在によって、セパレータ５Ａを構成する導電部材の導電性を確保しつつ、導電性炭素層を含まない場合と比較して耐食性が改善される。このような導電性炭素層としては、第一実施形態の導電性炭素層３３を使用することができる。 [Conductive thin film layer]
The conductive thin film layer 155 is disposed on the intermediate layer 154. Examples of the conductive thin film layer 155 include a metal thin film layer and a conductive carbon layer formed from carbon. Among these, as a material which comprises a metal thin film layer, copper (Cu), gold (Au), silver (Ag), platinum (Pt), palladium (Pd), etc. are mentioned. The conductive carbon layer is a layer containing conductive carbon. Of these, a conductive carbon layer is preferred. The presence of the conductive carbon layer improves the corrosion resistance as compared with the case where the conductive carbon layer is not included while ensuring the conductivity of the conductive member constituting the separator 5A. As such a conductive carbon layer, the conductive carbon layer 33 of the first embodiment can be used.
　次に、本実施形態の導電部材を製造するための好ましい実施形態を記載するが、本発明の技術的範囲は下記の形態のみには限定されない。また、セパレータ５Ａを構成する導電部材の各構成要素の材質などの諸条件については、上述した通りであるため、ここでは説明を省略する。 Next, a preferred embodiment for manufacturing the conductive member of the present embodiment will be described, but the technical scope of the present invention is not limited to the following embodiment. Moreover, since various conditions, such as the material of each component of the electrically-conductive member which comprises the separator 5A, are as above-mentioned, description is abbreviate | omitted here.
　本実施形態の導電部材の製造方法としては、まず、メッキ、溶射、ＣＶＤ又は塗布により、金属基材上に緻密バリア層を形成する［工程（１）］。次に、スパッタリング法又はイオンプレーティング法により、前記緻密バリア層上に中間層を形成する［工程（２）］。さらに、スパッタリング法又はイオンプレーティング法により、前記中間層上に導電性薄膜層を形成する［工程（３）］。 As a method for manufacturing the conductive member of this embodiment, first, a dense barrier layer is formed on a metal substrate by plating, spraying, CVD or coating [step (1)]. Next, an intermediate layer is formed on the dense barrier layer by sputtering or ion plating [Step (2)]. Further, a conductive thin film layer is formed on the intermediate layer by a sputtering method or an ion plating method [step (3)].
　［工程（１）］
　まず、金属基材として、所望の厚さのステンレス板やアルミニウム板などの金属板を準備する。次いで、第一実施形態と同様に、適当な溶媒を用いて、準備した金属基材の表面の脱脂及び洗浄処理を行う。続いて、金属基材の表面（両面）に形成されている酸化皮膜の除去を行う。酸化皮膜を除去するための手法としては、第一実施形態と同様の方法で行う。 [Step (1)]
First, a metal plate such as a stainless plate or an aluminum plate having a desired thickness is prepared as a metal substrate. Next, as in the first embodiment, the surface of the prepared metal substrate is degreased and cleaned using an appropriate solvent. Subsequently, the oxide film formed on the surface (both sides) of the metal substrate is removed. As a method for removing the oxide film, the same method as in the first embodiment is used.
　次に、上記処理を施した金属基材の表面に、緻密バリア層を形成する。ここで、緻密バリア層の形成方法は、上記したように結晶配向性が低くなるような方法であれば特に制限されないが、メッキ、溶射、ＣＶＤ（Ｃｈｅｍｉｃａｌ　Ｖａｐｏｒ　Ｄｅｐｏｓｉｔｉｏｎ）、及び塗布が使用される。好ましくは、メッキにより、緻密バリア層を金属基材の表面に形成する。 Next, a dense barrier layer is formed on the surface of the metal substrate subjected to the above treatment. Here, the method for forming the dense barrier layer is not particularly limited as long as the crystal orientation is lowered as described above, but plating, thermal spraying, CVD (Chemical Vapor Deposition), and coating are used. Preferably, the dense barrier layer is formed on the surface of the metal substrate by plating.
　メッキ条件としては、上記したような緻密バリア層が形成できるような条件であれば特に制限されず、公知の条件が使用され、使用される緻密バリア層の構成材料の種類や量などによって異なる。例えば、Ｃｒメッキ処理条件は、電流密度が３～１０Ａ／ｄｍ２、浴温度２０～６０℃、電析時間３０～１２０分である。このような条件によって、上記したような緻密バリア層が容易に形成される。 The plating conditions are not particularly limited as long as the above-described dense barrier layer can be formed. Known conditions are used, and vary depending on the type and amount of the constituent material of the dense barrier layer used. For example, Cr plating treatment conditions are a current density of 3 to 10 A / dm 2 , a bath temperature of 20 to 60 ° C., and an electrodeposition time of 30 to 120 minutes. Under such conditions, the dense barrier layer as described above can be easily formed.
　このような方法によって、結晶配向性の低い球状あるいは粒状組織（表面凸部）を有する緻密バリア層が金属基材上に形成できる。ここで、緻密バリア層の球状／粒状組織の大きさは、水分子を通過しない程度に細かいことが好ましい。具体的には、緻密バリア層の球状／粒状組織の平均結晶子径は、好ましくは１０ｎｍ～３０ｎｍ、より好ましくは１０ｎｍ～２０ｎｍである。このような大きさであると、水分子の浸入を有効に抑制できる。なお、「緻密バリア層の球状／粒状組織の平均結晶子径」は、Ｘ線回折によるピーク強度比の半値幅からＳｃｈｅｒｒｅｒの式を用いて算出する。 By such a method, a dense barrier layer having a spherical or granular structure (surface convex portion) with low crystal orientation can be formed on the metal substrate. Here, the size of the spherical / granular structure of the dense barrier layer is preferably fine enough not to pass water molecules. Specifically, the average crystallite diameter of the spherical / granular structure of the dense barrier layer is preferably 10 nm to 30 nm, more preferably 10 nm to 20 nm. With such a size, the penetration of water molecules can be effectively suppressed. The “average crystallite diameter of the spherical / granular structure of the dense barrier layer” is calculated using the Scherrer equation from the half-value width of the peak intensity ratio by X-ray diffraction.
　［工程（２）］
　次に、上記工程（１）で形成された緻密バリア層上に、中間層を形成する。ここで、中間層の形成方法は、上記したように結晶配向性がある程度高くなるような方法であれば特に制限されないが、第一実施形態と同様にスパッタリング法及びイオンプレーティング法が使用される。特にスパッタリング法が好ましい。 [Step (2)]
Next, an intermediate layer is formed on the dense barrier layer formed in the step (1). Here, the formation method of the intermediate layer is not particularly limited as long as the crystal orientation is high to some extent as described above, but the sputtering method and the ion plating method are used as in the first embodiment. . A sputtering method is particularly preferable.
　なお、中間層をスパッタリング法やイオンプレーティング法で緻密バリア層上に形成する場合には、緻密バリア層と中間層との境界部分は、緻密バリア層由来の緻密で結晶性の低い部分と、中間層由来の結晶性の高い柱状の部分とが、共存するような構造となっている場合がある。このような共存部分が存在したとしても、緻密で結晶性の低い緻密バリア層及び結晶性の高い柱状構造を有する中間層が上記したような厚みで配置されていれば、本発明による効果は十分達成できる。 When the intermediate layer is formed on the dense barrier layer by sputtering or ion plating, the boundary portion between the dense barrier layer and the intermediate layer is a dense and low crystallinity portion derived from the dense barrier layer, There may be a structure in which a columnar portion having high crystallinity derived from the intermediate layer coexists. Even if such coexisting portions exist, if the dense barrier layer having a low crystallinity and the intermediate layer having a columnar structure having a high crystallinity are arranged with the thickness as described above, the effect of the present invention is sufficient. Can be achieved.
　このような方法によって、緻密バリア層に比べて結晶配向性が高い柱状構造を有する中間層が緻密バリア層上に形成できる。ここで、中間層の柱状組織の大きさは特に制限されないが、緻密バリア層や導電性薄膜層との密着性などを考慮すると、上記緻密バリア層の球状／粒状組織の大きさよりも大きいことが好ましい。具体的には、中間層の柱状結晶の平均サイズ（平均太さ）は、好ましくは１０ｎｍ～１００ｎｍ、より好ましくは３０ｎｍ～１００ｎｍである。このような大きさであると、緻密バリア層や導電性薄膜層との密着性などを十分達成できる。なお、「中間層の柱状組織の平均サイズ」は、中間層の断面をＳＥＭで画像解析することにより算出する。 By such a method, an intermediate layer having a columnar structure having higher crystal orientation than the dense barrier layer can be formed on the dense barrier layer. Here, the size of the columnar structure of the intermediate layer is not particularly limited, but it may be larger than the size of the spherical / granular structure of the dense barrier layer in consideration of adhesion to the dense barrier layer and the conductive thin film layer. preferable. Specifically, the average size (average thickness) of the columnar crystals in the intermediate layer is preferably 10 nm to 100 nm, more preferably 30 nm to 100 nm. With such a size, sufficient adhesion with the dense barrier layer and the conductive thin film layer can be achieved. The “average size of the columnar structure of the intermediate layer” is calculated by image analysis of the cross section of the intermediate layer with an SEM.
　［工程（３）］
　次に、上記工程（２）で形成された中間層上に、導電性薄膜層を形成する。ここで、導電性薄膜層の形成方法は、導電性薄膜層が導電性炭素からなる場合、第一実施形態と同様の方法で作成することができる。 [Step (3)]
Next, a conductive thin film layer is formed on the intermediate layer formed in the step (2). Here, when the conductive thin film layer is made of conductive carbon, the conductive thin film layer can be formed by the same method as in the first embodiment.
　上述した手法によれば、金属基材１５２、緻密バリア層１５３、中間層１５４及び導電性薄膜層１５５が順次形成された導電部材を製造することができる。なお、上記手法では、金属基材１５２の片面にのみ、緻密バリア層１５３、中間層１５４及び導電性薄膜層１５５を形成したが、金属基材１５２の両面に上記各層が形成されてなる導電部材を製造するには、金属基材１５２の他方の面に対して、上記と同様の手法を適用すれば良い。 According to the above-described method, a conductive member in which the metal base 152, the dense barrier layer 153, the intermediate layer 154, and the conductive thin film layer 155 are sequentially formed can be manufactured. In the above method, the dense barrier layer 153, the intermediate layer 154, and the conductive thin film layer 155 are formed only on one side of the metal base material 152, but a conductive member in which the above layers are formed on both sides of the metal base material 152. In order to manufacture, the same method as described above may be applied to the other surface of the metal substrate 152.
　本実施形態の導電部材は、第一実施形態と同様に、種々の用途に用いることができる。その代表例がＰＥＦＣのセパレータ５Ａである。上記導電部材をＰＥＦＣのセパレータに使用する場合、アノード及びカソードの少なくともいずれか一方に使用されれば良い。しかし、特にカソード側で水が多量に生成することなどを考慮すると、上記導電部材を少なくともカソードセパレータとして使用することが好ましい。より好ましくは、本実施形態の導電部材を、カソードセパレータ及びアノードセパレータ双方に使用する。なお、本実施形態では、緻密バリア層は、双方のセパレータについて金属基材の全面にわたって被覆されている必要はない。ただし、金属基材への水の浸入抑制効果を考慮すると、カソードセパレータでの被覆率の方が、アノードセパレータでの被覆率と同等以上であることが好ましい。これにより、より多量の水が生成するカソード側での水分子の浸入を有効に抑制して、導電部材（特に、金属基材）の導電性・耐食性の低下を効果的に抑制することができる。具体的には、カソードセパレータ側に対するアノードセパレータ側での緻密バリア層による金属基材の被覆率の大小関係は、カソードセパレータ側での被覆率を１００とすると、アノード側は、好ましくは６０～１００であり、より好ましくは８０～１００である。 The conductive member of the present embodiment can be used for various applications as in the first embodiment. A typical example is a PEFC separator 5A. When the conductive member is used for a PEFC separator, it may be used for at least one of an anode and a cathode. However, considering the generation of a large amount of water on the cathode side, it is preferable to use the conductive member as at least a cathode separator. More preferably, the conductive member of this embodiment is used for both the cathode separator and the anode separator. In the present embodiment, the dense barrier layer does not need to be covered over the entire surface of the metal substrate for both separators. However, in consideration of the effect of suppressing the penetration of water into the metal substrate, the coverage with the cathode separator is preferably equal to or higher than the coverage with the anode separator. Thereby, it is possible to effectively suppress the intrusion of water molecules on the cathode side where a larger amount of water is generated, and to effectively suppress the decrease in the conductivity and corrosion resistance of the conductive member (particularly, the metal substrate). . Specifically, the relationship of the coverage of the metal substrate with the dense barrier layer on the anode separator side relative to the cathode separator side is preferably 60 to 100 on the anode side, assuming that the coverage on the cathode separator side is 100. More preferably, it is 80-100.
　また、カソード側及びアノード側セパレータのそれぞれの面方向についても、緻密バリア層は必ずしも金属基材の全面にわたって（被覆率１００％で）形成される必要はない。好ましくは、緻密バリア層は、各セパレータの面内分布として、連続的にもしくは二領域以上の分割領域で、ガス流れ方向に対して下流側ほど高い被覆率になるように、金属基材上に形成される。これは、カソード及びアノード双方において、ガス流れ方向に対して下流側ほど水が多量に生成することを考慮したものである。ゆえに、このような配置とすることによって、水の生成量に応じて緻密バリア層が金属基材上に形成され、水分子の浸入をより有効に抑制して、導電部材の導電性・耐食性の低下をより効果的に抑制できる。 Also, in each of the surface directions of the cathode side and the anode side separator, the dense barrier layer does not necessarily have to be formed over the entire surface of the metal substrate (with a coverage of 100%). Preferably, the dense barrier layer is formed on the metal substrate so that the in-plane distribution of each separator is continuously or divided into two or more regions so that the downstream side of the gas flow direction has a higher coverage. It is formed. This is due to the fact that a large amount of water is generated at the cathode and anode at the downstream side with respect to the gas flow direction. Therefore, by adopting such an arrangement, a dense barrier layer is formed on the metal substrate according to the amount of water generated, and the invasion of water molecules is more effectively suppressed, and the conductivity and corrosion resistance of the conductive member are reduced. Reduction can be suppressed more effectively.
　本実施形態の導電部材は、第一実施形態の導電部材と同様に、ＰＥＦＣ以外にも、ＰＡＦＣ、ＭＣＦＣ、ＳＯＦＣ又はＡＦＣなどの各種の燃料電池用セパレータとしても使用可能である。また、燃料電池用セパレータ以外にも、他の燃料電池部品（集電板、バスバー、ガス拡散基体、ＭＥＡ）、電子部品の接点などに使用可能である。さらに、本実施形態の導電部材は、湿潤環境及び通電環境の下で使用することができる。そのような環境下で用いると、導電性及び耐食性の両立を図るという本発明の作用効果が顕著に発現する。 The conductive member of this embodiment can be used as a separator for various fuel cells such as PAFC, MCFC, SOFC, or AFC in addition to PEFC, similarly to the conductive member of the first embodiment. In addition to the fuel cell separator, it can be used for other fuel cell components (current collector plate, bus bar, gas diffusion base, MEA), electronic component contacts, and the like. Furthermore, the conductive member of this embodiment can be used in a wet environment and an energized environment. When used in such an environment, the effect of the present invention of achieving both conductivity and corrosion resistance is remarkably exhibited.
　以下、本実施形態の導電部材の効果を、参考例、実施例及び比較例を用いてさらに説明するが、本発明の技術的範囲はこれらの実施例に限定されない。 Hereinafter, the effects of the conductive member of the present embodiment will be further described using reference examples, examples, and comparative examples, but the technical scope of the present invention is not limited to these examples.
　［参考例II－１］
　金属基材として、アルミニウム板（厚さ：０．２ｍｍ）を準備した。このアルミニウム板について、ｐＨ１０のアルカリ水溶液中に５０℃で１０分間、浸漬洗浄を行った。次に、このアルミニウム板を硝酸でエッチングすることにより、酸化皮膜を除去した。さらに、アルミニウム板を、ふっ酸混酸液による表面活性化を行った後、亜鉛置換浴にてジンケート処理を行った。なお、この際、ジンケート処理条件は、浴温度２５℃、浸漬時間３０秒である。また、上記前記処理は、アルミニウム板の両面について行った。 [Reference Example II-1]
An aluminum plate (thickness: 0.2 mm) was prepared as a metal substrate. This aluminum plate was immersed and washed in an alkaline aqueous solution of pH 10 at 50 ° C. for 10 minutes. Next, the oxide film was removed by etching the aluminum plate with nitric acid. Further, the aluminum plate was subjected to surface activation with a hydrofluoric acid mixed acid solution and then subjected to a zincate treatment in a zinc substitution bath. In this case, the zincate treatment conditions are a bath temperature of 25 ° C. and an immersion time of 30 seconds. Moreover, the said process was performed about both surfaces of the aluminum plate.
　次に、上記前処理を行ったアルミニウム板について、サージェント浴にてクロムメッキを行い、緻密バリア層を形成した。この際、メッキ処理条件は、電流密度４Ａ／ｄｍ２、浴温度３５℃、電析時間１時間であり、これにより膜厚２μｍのＣｒからなる緻密バリア層（Ｃｒメッキ）を形成した。 Next, the pretreated aluminum plate was subjected to chrome plating in a sergeant bath to form a dense barrier layer. At this time, the plating treatment conditions were a current density of 4 A / dm 2 , a bath temperature of 35 ° C., and an electrodeposition time of 1 hour, whereby a dense barrier layer (Cr plating) made of Cr having a thickness of 2 μm was formed.
　このようにして形成された緻密バリア層について、Ｘ線回折法におけるＳｃｈｅｒｒｅの方法によって平均結晶子径を測定したところ、１５ｎｍであった。なお、Ｘ線回折装置としては、マックサイエンス社製を用いた。 The average crystallite diameter of the dense barrier layer thus formed was measured by the Scherre method in the X-ray diffraction method and found to be 15 nm. In addition, as an X-ray diffraction apparatus, the product made by Mac Science Co., Ltd. was used.
　また、このようにして形成された緻密バリア層について、断面をＳＥＭにより画像解析を行い、Ｃｒメッキの占める面積率を測定することによって、空隙率を求めた。その結果、空隙率は１％以下であった。 Further, with respect to the dense barrier layer thus formed, the cross section was subjected to image analysis by SEM, and the area ratio occupied by Cr plating was measured to obtain the porosity. As a result, the porosity was 1% or less.
　［参考例II－２］
　導電部材を構成する金属基材として、アルミニウム板（厚さ：０．２ｍｍ）を準備した。このアルミニウム板について、前処理としてエタノール水溶液中で３分間超音波洗浄した。次いで、洗浄したアルミニウム板を真空チャンバ内に設置し、Ａｒガスによるイオンボンバード処理を行って、表面の酸化皮膜を除去した。なお、上述した前処理及びイオンボンバード処理は、いずれもアルミニウム板の両面に対して行った。 [Reference Example II-2]
An aluminum plate (thickness: 0.2 mm) was prepared as a metal substrate constituting the conductive member. This aluminum plate was subjected to ultrasonic cleaning in an aqueous ethanol solution for 3 minutes as a pretreatment. Next, the cleaned aluminum plate was placed in a vacuum chamber, and ion bombardment with Ar gas was performed to remove the oxide film on the surface. The pretreatment and ion bombardment described above were both performed on both sides of the aluminum plate.
　次に、ＵＢＭＳ法により、Ｃｒをターゲットとして、アルミニウム板に対して５０Ｖの大きさの負のバイアス電圧を印加しながら、アルミニウム板上に中間層を形成した。Ｃｒからなる中間層の厚さは、０．２μｍであった。 Next, an intermediate layer was formed on the aluminum plate by UBMS while applying a negative bias voltage of 50 V to the aluminum plate using Cr as a target. The thickness of the intermediate layer made of Cr was 0.2 μm.
　このようにして形成された中間層について、参考例II－１と同様にして平均結晶子径を測定したところ、３０ｎｍであった。また、この中間層について、参考例II－１と同様にして空隙率を求めたところ、７％であった。 The average crystallite diameter of the thus formed intermediate layer was measured in the same manner as in Reference Example II-1, and found to be 30 nm. Further, when the porosity of this intermediate layer was determined in the same manner as in Reference Example II-1, it was 7%.
　ここで、参考例II－１の結果と参考例II－２の結果とを比較することによって、参考例II－１で形成した緻密バリア層は、本例で形成した中間層に比べて、空隙率が低いことが分かる。また、参考例II－１で形成した緻密バリア層の平均結晶子径［Ｄ２（ｎｍ）］は、本例で形成した中間層の平均結晶子径［Ｄ１（ｎｍ）］に比べて、小さい（Ｄ２／Ｄ１＝０．５）。一方、結晶配向度（結晶配向性）と平均結晶子径とは相関関係があるため、参考例II－１で形成した緻密バリア層は、本例で形成した中間層に比べて、結晶配向性が低いことが考察される。また、平均結晶子径を調節することによって、各層の結晶配向度を容易に調節できることも考察される。 Here, by comparing the result of Reference Example II-1 with the result of Reference Example II-2, the dense barrier layer formed in Reference Example II-1 was more void than the intermediate layer formed in this Example. It can be seen that the rate is low. In addition, the average crystallite diameter [D 2 (nm)] of the dense barrier layer formed in Reference Example II-1 is larger than the average crystallite diameter [D 1 (nm)] of the intermediate layer formed in this example. small (D 2 / D 1 = 0.5 ). On the other hand, since the degree of crystal orientation (crystal orientation) has a correlation with the average crystallite diameter, the dense barrier layer formed in Reference Example II-1 has a crystal orientation higher than that of the intermediate layer formed in this example. Is considered low. It is also considered that the degree of crystal orientation of each layer can be easily adjusted by adjusting the average crystallite size.
　さらに、上記参考例II－１及び２で作製された緻密バリア層及び中間層の断面を、ＴＥＭにより画像解析を行った結果を、図２２Ａ（参考例II－１）及び図２２Ｂ（参考例II－２）に示す。図２２Ａ及び図２２Ｂから、参考例II－１の緻密バリア層は粒状組織を有するのに対して、参考例II－２の中間層は、柱状組織を有することが分かる。また、この図からも、参考例II－１の緻密バリア層の方が、参考例II－２の中間層に比べて緻密であることが分かり、この結果は、上記空隙率の結果と一致するものである。 Further, the results of image analysis of the cross sections of the dense barrier layer and the intermediate layer prepared in Reference Examples II-1 and II by TEM are shown in FIG. 22A (Reference Example II-1) and FIG. 22B (Reference Example II). -2). 22A and 22B that the dense barrier layer of Reference Example II-1 has a granular structure, while the intermediate layer of Reference Example II-2 has a columnar structure. Also from this figure, it can be seen that the dense barrier layer of Reference Example II-1 is denser than the intermediate layer of Reference Example II-2, and this result agrees with the result of the porosity described above. Is.
　同様にして、上記参考例II－１及びII－２で作製された緻密バリア層及び中間層について、各層の表面をＳＥＭにより画像解析を行い、その結果を図２３Ａ（参考例II－１）及び図２３Ｂ（参考例II－２）に示す。図２３Ａ及び図２３Ｂから、参考例II－１の緻密バリア層では細かい粒状組織が形成されているのに対して、参考例II－２の中間層では一定間隔の隙間がある凸部が形成していることもわかる。また、図２３Ｂから、中間層の柱状組織の平均サイズ（平均太さ）は約５０ｎｍであることが分かった。 Similarly, with respect to the dense barrier layer and the intermediate layer prepared in Reference Examples II-1 and II-2, the surface of each layer was subjected to image analysis by SEM, and the results are shown in FIG. 23A (Reference Example II-1) and This is shown in FIG. 23B (Reference Example II-2). From FIG. 23A and FIG. 23B, the fine barrier layer of Reference Example II-1 has a fine granular structure, whereas the intermediate layer of Reference Example II-2 has convex portions with gaps of a constant interval. You can see that Moreover, from FIG. 23B, it turned out that the average size (average thickness) of the columnar structure of the intermediate layer is about 50 nm.
　さらに、上記参考例II－１及びII－２で作製された緻密バリア層及び中間層の詳細なＳＥＭ写真を図２３Ｃ（参考例II－１）及び図２３Ｄ（参考例II－２）に示す。図２３Ｃに示すように、緻密バリア層では粒状又は球状のクロム粒子１５３ａが緻密に凝集しており、緻密バリア層１５３の空隙率が極めて低いことが確認できる。さらにクロム粒子１５３ａの結晶軸が様々な方向で存在しており、結晶配向性が低いこともわかる。これに対し、図２３Ｄに示すように、中間層１５４では柱状のクロム粒子１５４ａ間に若干の隙間１５４ｂが見られ、緻密バリア層１５３に比べ空隙率が高いことがわかる。また、柱状のクロム粒子１５４ａは図面の下方から上方に向けて配向しており、緻密バリア層１５３のクロム粒子１５３ａに比べ結晶配向性が高いことがわかる。 Further, detailed SEM photographs of the dense barrier layer and the intermediate layer prepared in Reference Examples II-1 and II-2 are shown in FIG. 23C (Reference Example II-1) and FIG. 23D (Reference Example II-2). As shown in FIG. 23C, it can be confirmed that granular or spherical chromium particles 153a are densely aggregated in the dense barrier layer, and the porosity of the dense barrier layer 153 is extremely low. Further, it can be seen that the crystal axes of the chromium particles 153a are present in various directions, and the crystal orientation is low. On the other hand, as shown in FIG. 23D, in the intermediate layer 154, a slight gap 154b is seen between the columnar chromium particles 154a, and it can be seen that the porosity is higher than that of the dense barrier layer 153. In addition, it can be seen that the columnar chromium particles 154a are oriented from the lower side to the upper side of the drawing and have higher crystal orientation than the chromium particles 153a of the dense barrier layer 153.
　［実施例II－１］
　参考例II－１に記載の方法と同様にして、金属基材の両面に、膜厚２μｍのＣｒからなる緻密バリア層（Ｃｒメッキ、平均結晶子径：１５ｎｍ）を形成した。次に、一方の面の緻密バリア層に対して、参考例II－２に記載の方法と同様にして、ＵＢＭＳ法により、Ｃｒをターゲットとして、負のバイアス電圧（５０Ｖ）を印加しながら、０．２μｍの厚さのＣｒからなる中間層（平均結晶子径：３０ｎｍ）を形成した。さらに同様の操作を繰り返して、他方の面の緻密バリア層上に０．２μｍの厚さのＣｒからなる中間層を形成した。これにより、０．２μｍの厚さのＣｒからなる中間層；膜厚２μｍのＣｒからなる緻密バリア層；金属基材；膜厚２μｍのＣｒからなる緻密バリア層；０．２μｍの厚さのＣｒからなる中間層の５層の積層体を作製した。 [Example II-1]
In the same manner as described in Reference Example II-1, a dense barrier layer (Cr plating, average crystallite diameter: 15 nm) made of Cr having a thickness of 2 μm was formed on both surfaces of the metal substrate. Next, in the same manner as described in Reference Example II-2, while applying a negative bias voltage (50 V) using Cr as a target to the dense barrier layer on one surface by the UBMS method, An intermediate layer (average crystallite diameter: 30 nm) made of Cr having a thickness of 2 μm was formed. Further, the same operation was repeated to form an intermediate layer made of Cr having a thickness of 0.2 μm on the dense barrier layer on the other surface. Thus, an intermediate layer made of Cr having a thickness of 0.2 μm; a dense barrier layer made of Cr having a thickness of 2 μm; a metal substrate; a dense barrier layer made of Cr having a thickness of 2 μm; a Cr having a thickness of 0.2 μm A laminate of 5 intermediate layers was prepared.
　この積層体を３０ｍｍ×３０ｍｍの大きさに切断し、側面をシリコン材でマスキングして、サンプル（II－１）を調製した。 The laminate was cut into a size of 30 mm × 30 mm, and the side surface was masked with a silicon material to prepare a sample (II-1).
　［比較例II－１］
　参考例II－１に記載の方法と同様にして、金属基材の両面に、膜厚２μｍのＣｒからなる緻密バリア層（Ｃｒメッキ）を形成した。これを３０ｍｍ×３０ｍｍの大きさに切断し、側面をシリコン材でマスキングして、サンプル（II－２）を調製した。 [Comparative Example II-1]
In the same manner as described in Reference Example II-1, a dense barrier layer (Cr plating) made of Cr having a thickness of 2 μm was formed on both surfaces of the metal substrate. This was cut into a size of 30 mm × 30 mm, and the side surface was masked with a silicon material to prepare sample (II-2).
　［比較例II－２］
　参考例II－２に記載の方法と同様にして、金属基材の両面に、０．２μｍの厚さのＣｒからなる中間層を形成した。これを３０ｍｍ×３０ｍｍの大きさに切断し、側面をシリコン材でマスキングして、サンプル（II－３）を調製した。 [Comparative Example II-2]
In the same manner as described in Reference Example II-2, an intermediate layer made of Cr having a thickness of 0.2 μm was formed on both surfaces of the metal substrate. This was cut into a size of 30 mm × 30 mm, and the side surface was masked with a silicon material to prepare sample (II-3).
　［評価：耐食性試験］
　上記実施例II－１並びに比較例II－１及びII－２で作製したサンプル（II－１）、（II－２）、（II－３）について、以下のような実験を行って、アルミニウムイオンの溶出量を試験した。すなわち、上記サンプル（II－１）、（II－２）及び（II－３）を、それぞれ硫酸水溶液（ｐＨ４）７０ｍＬ中に、８０℃で１００時間浸漬した。なお上記硫酸水溶液は、燃料電池においてセパレータが曝される環境を模擬したものである。また、一般的に燃料電池運転時の温度は８０℃であるため、試験温度を８０℃に設定した。 [Evaluation: Corrosion resistance test]
For the samples (II-1), (II-2), and (II-3) prepared in Example II-1 and Comparative Examples II-1 and II-2, the following experiment was conducted to obtain aluminum ions. The amount of elution was tested. That is, the samples (II-1), (II-2) and (II-3) were each immersed in 70 mL of sulfuric acid aqueous solution (pH 4) at 80 ° C. for 100 hours. The sulfuric acid aqueous solution simulates the environment where the separator is exposed in the fuel cell. Further, since the temperature during operation of the fuel cell is generally 80 ° C., the test temperature was set to 80 ° C.
　１００時間経過後の、硫酸水溶液中に溶出したアルミニウムイオンの量（ｐｐｍ）を、ＩＣＰ－ＭＳ（Ｉｎｄｕｃｔｉｖｅｌｙ－Ｃｏｕｐｌｅｄ　Ｐｌａｓｍａ－Ｍａｓｓ　Ｓｐｅｃｔｒｏｍｅｔｒｙ）によって分析した。その結果を下記表３に示す。 After 100 hours, the amount (ppm) of aluminum ions eluted in the sulfuric acid aqueous solution was analyzed by ICP-MS (Inductively-Coupled Plasma-Mass Spectrometry). The results are shown in Table 3 below.
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
　［実施例II－２］
　参考例II－１に記載の方法と同様にして、金属基材の一方の面に、膜厚２μｍのＣｒからなる緻密バリア層（Ｃｒメッキ、平均結晶子径：１５ｎｍ）を形成した。次に、形成された緻密バリア層に対して、参考例II－２に記載の方法と同様にして、ＵＢＭＳ法により、Ｃｒをターゲットとして、負のバイアス電圧（５０Ｖ）を印加しながら、０．２μｍの厚さのＣｒからなる中間層（平均結晶子径：３０ｎｍ）を形成した。 [Example II-2]
In the same manner as described in Reference Example II-1, a dense barrier layer (Cr plating, average crystallite diameter: 15 nm) made of Cr having a thickness of 2 μm was formed on one surface of the metal substrate. Next, in the same manner as described in Reference Example II-2, a negative bias voltage (50 V) is applied to the formed dense barrier layer by the UBMS method while applying a negative bias voltage (50 V). An intermediate layer (average crystallite diameter: 30 nm) made of Cr having a thickness of 2 μm was formed.
　さらに、ＵＢＭＳ法により、固体グラファイトをターゲットとして、中間層に対して１００Ｖの大きさの負のバイアス電圧を印加しながら、中間層上に０．２μｍの厚さの導電性薄膜層を形成した。これにより、本実施例の導電部材を作製した。 Further, a conductive thin film layer having a thickness of 0.2 μm was formed on the intermediate layer by applying a negative bias voltage having a magnitude of 100 V to the intermediate layer, using solid graphite as a target, by the UBMS method. Thus, the conductive member of this example was produced.
　この導電部材の断面を、ＴＥＭにより画像解析を行った結果を、図２４に示す。図２４から、本実施形態の導電部材では、緻密バリア層は粒状組織に形成されるのに対して、中間層は柱状組織に形成されており、緻密バリア層の方が中間層に比べてより緻密であることが分かる。この結果は、上記空隙率の結果と一致するものである。 FIG. 24 shows the result of image analysis of the cross section of the conductive member by TEM. From FIG. 24, in the conductive member of this embodiment, the dense barrier layer is formed in a granular structure, whereas the intermediate layer is formed in a columnar structure, and the dense barrier layer is more in comparison with the intermediate layer. It turns out that it is precise. This result is consistent with the porosity result.
［第三実施形態］
　次に、本発明の第三実施形態に係る導電部材及びその製造方法について、図面に基づき詳細に説明する。なお、第一実施形態と同一構成には同一符号を付し、重複する説明は省略する。 [Third embodiment]
Next, the conductive member and the manufacturing method thereof according to the third embodiment of the present invention will be described in detail with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same structure as 1st embodiment, and the overlapping description is abbreviate | omitted.
　本実施形態の導電部材（導電構造体）は、金属基材、中間層及び導電性炭素層が順に積層されてなる。そして、前記金属基材と中間層との間に導電性粒子を含む導電性補強層を有する。 The conductive member (conductive structure) of this embodiment is formed by laminating a metal base material, an intermediate layer, and a conductive carbon layer in this order. And it has the electroconductive reinforcement layer containing electroconductive particle between the said metal base material and an intermediate | middle layer.
　本実施形態は、金属基材と中間層との間に導電性粒子が存在する。そのため、金属基材や中間層の酸化に起因する酸化皮膜が形成された場合であっても、導電性粒子が導電パスを形成し、導電性を維持できる。導電性補強層は、抵抗値の上昇を抑制することに起因した層間の導電性向上のみならず、耐食性にも優れている。したがって、本実施形態の導電部材は優れた導電性及び耐食性を共に達成することができる。このため、上記導電部材をセパレータとして使用する燃料電池は、金属セパレータの優れた導電性を十分に確保しつつ、優れた耐久性を発揮できる。 In this embodiment, conductive particles exist between the metal substrate and the intermediate layer. Therefore, even when the oxide film resulting from the oxidation of the metal substrate or the intermediate layer is formed, the conductive particles can form a conductive path and maintain conductivity. The conductive reinforcing layer has excellent corrosion resistance as well as improved conductivity between layers caused by suppressing an increase in resistance value. Therefore, the conductive member of this embodiment can achieve both excellent conductivity and corrosion resistance. For this reason, the fuel cell using the said electrically-conductive member as a separator can exhibit the outstanding durability, fully ensuring the outstanding electroconductivity of a metal separator.
　本実施形態に係る固体高分子形燃料電池（ＰＥＦＣ）も第一実施形態に係るＰＥＦＣと同様の基本構成を有する。具体的には、図１に示すように、ＰＥＦＣは、固体高分子電解質膜２と、これを挟持する一対の触媒層３（アノード触媒層３ａ及びカソード触媒層３ｂ）とを有する。そして、固体高分子電解質膜２と触媒層（３ａ、３ｂ）との積層体はさらに、一対のガス拡散層（ＧＤＬ）４（アノードガス拡散層４ａ及びカソードガス拡散層４ｂ）により挟持されている。このように、固体高分子電解質膜２、一対の触媒層３（３ａ、３ｂ）及び一対のガス拡散層４（４ａ、４ｂ）は、積層された状態で膜電極接合体（ＭＥＡ）９を構成する。ＭＥＡ９はさらに、一対のセパレータ５（アノードセパレータ５ａ及びカソードセパレータ５ｂ）により挟持されている。 The polymer electrolyte fuel cell (PEFC) according to this embodiment also has the same basic configuration as the PEFC according to the first embodiment. Specifically, as shown in FIG. 1, the PEFC has a solid polymer electrolyte membrane 2 and a pair of catalyst layers 3 (an anode catalyst layer 3a and a cathode catalyst layer 3b) that sandwich the membrane. The laminate of the solid polymer electrolyte membrane 2 and the catalyst layers (3a, 3b) is further sandwiched between a pair of gas diffusion layers (GDL) 4 (anode gas diffusion layer 4a and cathode gas diffusion layer 4b). . Thus, the solid polymer electrolyte membrane 2, the pair of catalyst layers 3 (3a, 3b), and the pair of gas diffusion layers 4 (4a, 4b) constitute a membrane electrode assembly (MEA) 9 in a stacked state. To do. The MEA 9 is further sandwiched between a pair of separators 5 (an anode separator 5a and a cathode separator 5b).
　図２５は、本実施形態の導電部材たるセパレータ５Ｂの構成を示す断面図である。本実施形態において、セパレータ５Ｂは、金属基材２５２と、中間層２５６と、導電性炭素層２５４とを有する。そして、金属基材２５２と中間層２５６との間には、導電性補強層２５５が介在している。なお、ＰＥＦＣにおいて、セパレータ５Ｂは、導電性炭素層２５４がＭＥＡ９側に位置するように、配置される。以下、本実施形態のセパレータ５Ｂの各構成要素について詳述する。 FIG. 25 is a cross-sectional view showing a configuration of a separator 5B which is a conductive member of the present embodiment. In the present embodiment, the separator 5 </ b> B includes a metal base 252, an intermediate layer 256, and a conductive carbon layer 254. A conductive reinforcing layer 255 is interposed between the metal base 252 and the intermediate layer 256. In the PEFC, the separator 5B is arranged so that the conductive carbon layer 254 is located on the MEA 9 side. Hereinafter, each component of the separator 5B of this embodiment is explained in full detail.
　［金属基材］
　金属基材２５２は、セパレータ５Ｂを構成する導電部材の主層であり、導電性及び機械的強度の確保に寄与する。そして、本実施形態に係る金属基材２５２は、第一実施形態の金属基材３１と同様のものを使用することができる。 [Metal base material]
The metal base 252 is a main layer of a conductive member that constitutes the separator 5B, and contributes to ensuring conductivity and mechanical strength. And the metal base material 252 which concerns on this embodiment can use the thing similar to the metal base material 31 of 1st embodiment.
　なお、本実施形態では、金属基材２５２の少なくとも一方の表面に酸化皮膜が形成されていても良い。酸化皮膜は、金属基材を空気中に放置することにより自然形成されたものであっても、あるいは酸化雰囲気（ガス、溶液）中で人工的に金属基材を酸化したものであっても良い。例えば、金属基材がステンレスから形成される場合には、Ｃｒ２Ｏ３、ＮｉＯ、Ｆｅ２Ｏ３を含む。金属基材がアルミニウムから形成される場合には、Ａｌ２Ｏ３を含む。金属基材が鉄から形成される場合には、Ｆｅ２Ｏ３を含む。金属基材がチタンから形成される場合には、ＴｉＯ２を含む。 In the present embodiment, an oxide film may be formed on at least one surface of the metal substrate 252. The oxide film may be formed naturally by leaving the metal substrate in the air, or may be an artificially oxidized metal substrate in an oxidizing atmosphere (gas, solution). . For example, when a metal base material is formed from stainless steel, it contains Cr 2 O 3 , NiO, and Fe 2 O 3 . In the case where the metal substrate is made of aluminum, Al 2 O 3 is included. When the metal substrate is made of iron, it contains Fe 2 O 3 . When the metal substrate is formed from titanium, including TiO 2.
　［導電性補強層］
　導電性補強層２５５は、導電性粒子を含む層であり、金属基材２５２上に配置される。この層の存在によって、金属基材上又は後述する中間層内部に酸化被膜が形成された場合であっても、十分な導電性が確保される。ゆえに、導電性補強層２５５の配置により、セパレータ５を構成する導電部材は、耐食性を確保しつつ、金属基材２５２、中間層２５６及び導電性炭素層２５４のみを有する導電部材に比べて、導電性を向上させることができる。 [Conductive reinforcement layer]
The conductive reinforcing layer 255 is a layer containing conductive particles, and is disposed on the metal substrate 252. Due to the presence of this layer, sufficient conductivity is ensured even when an oxide film is formed on the metal substrate or in the intermediate layer described later. Therefore, due to the arrangement of the conductive reinforcing layer 255, the conductive member constituting the separator 5 is more conductive than the conductive member having only the metal substrate 252, the intermediate layer 256, and the conductive carbon layer 254 while ensuring corrosion resistance. Can be improved.
　導電性粒子は、導電性を有しかつ酸化物を形成しない材料であれば、特に制限されない。具体的には、貴金属元素、貴金属元素を含む合金、及びカーボンからなる群より選択される少なくとも一種であることが好ましい。そのような場合には、酸性水が層内に侵入した場合であっても、導電性粒子は酸化被膜を形成しないため、良好な導電性を維持することができる。貴金属元素としては、金（Ａｕ）、銀（Ａｇ）、白金（Ｐｔ）、パラジウム（Ｐｄ）、ロジウム（Ｒｈ）、イリジウム（Ｉｒ）、ルテニウム（Ｒｕ）及びオスミウム（Ｏｓ）よりなる群から選択される少なくとも一種が好ましく挙げられる。貴金属を含む合金としては、金－コバルト合金（Ａｕ－Ｃｏ）、金－ニッケル合金（Ａｕ－Ｎｉ）、パラジウム－ニッケル合金（Ｐｄ－Ｎｉ）などが挙げられる。カーボンとしては、グラファイト、カーボンブラック、無定形炭素、活性炭、コークス、及びガラス状カーボンよりなる群から選択される少なくとも一種が好ましく挙げられる。なかでも、比較的安価なグラファイトが好ましい。なお、これらの貴金属、貴金属元素を含む合金、又はカーボンの種類については、一種単独で用いてもよく、二種以上を混合させて用いても良い。また、導電性粒子は中間層を構成する材料とは異なる材料を含むことが好ましい。そのような場合には、中間層とは異なる特性や機能を導電性補強層に付与することが可能となる。 The conductive particles are not particularly limited as long as they are conductive and do not form oxides. Specifically, it is preferably at least one selected from the group consisting of noble metal elements, alloys containing noble metal elements, and carbon. In such a case, even when acidic water penetrates into the layer, the conductive particles do not form an oxide film, so that good conductivity can be maintained. The noble metal element is selected from the group consisting of gold (Au), silver (Ag), platinum (Pt), palladium (Pd), rhodium (Rh), iridium (Ir), ruthenium (Ru) and osmium (Os). Preferably, at least one of these is preferred. Examples of the alloy containing a noble metal include a gold-cobalt alloy (Au—Co), a gold-nickel alloy (Au—Ni), a palladium-nickel alloy (Pd—Ni), and the like. Preferred examples of carbon include at least one selected from the group consisting of graphite, carbon black, amorphous carbon, activated carbon, coke, and glassy carbon. Of these, relatively inexpensive graphite is preferable. In addition, about the kind of these noble metals, the alloy containing a noble metal element, or carbon, you may use individually by 1 type, and may mix and use 2 or more types. Moreover, it is preferable that electroconductive particle contains the material different from the material which comprises an intermediate | middle layer. In such a case, it is possible to impart characteristics and functions different from those of the intermediate layer to the conductive reinforcing layer.
　導電性粒子の平均粒子径は、金属基材又は中間層の表面に形成される酸化被膜の厚さ以上であることが好ましい。具体的には、上記酸化被膜の厚さを予め測定し、導電性粒子の平均粒子径をその酸化被膜の厚さ以上とすれば良い。酸化被膜の厚さの測定方法としては、例えば、基材金属又は中間層を構成する材料を酸性雰囲気下に一定時間放置させた後、材料の表面に形成された酸化被膜の厚さをオージェ電子分光法（ＡＥＳ）などによって測定する方法が挙げられる。簡便な方法としては、酸性水に一定時間浸水させた材料について酸化被膜の厚さを測定すれば良い。 The average particle diameter of the conductive particles is preferably equal to or greater than the thickness of the oxide film formed on the surface of the metal substrate or intermediate layer. Specifically, the thickness of the oxide film may be measured in advance, and the average particle diameter of the conductive particles may be equal to or greater than the thickness of the oxide film. As a method for measuring the thickness of the oxide film, for example, after the material constituting the base metal or the intermediate layer is allowed to stand in an acidic atmosphere for a certain period of time, the thickness of the oxide film formed on the surface of the material is determined by Auger electron. The method of measuring by spectroscopy (AES) etc. is mentioned. As a simple method, the thickness of the oxide film may be measured for a material immersed in acidic water for a certain period of time.
　図２６は、８０℃、ｐＨ４の硫酸水溶液に１００時間浸漬した金属基材（ＳＵＳ３１６Ｌ）を、オージェ電子分光法を用いて元素濃度を計測した結果を示す図面である。金属基材の構成元素（Ｆｅ、Ｃｒ、Ｎｉ）の他に、表面酸化物に由来する酸素（Ｏ’）が表層からの深さ約１０ｎｍに存在することがわかる。したがって、そのような条件においては、導電性粒子の平均粒子径は１０ｎｍ以上であることが好ましく、１０ｎｍ～１００ｎｍであることがより好ましく、１０ｎｍ～２０ｎｍであることがさらに好ましい。なお、電池内の酸性雰囲気は発電条件によって変わるため、表面酸化物の厚さの事前評価は、発電条件に応じた電池内環境を模擬した条件で行うことが望ましい。 FIG. 26 is a drawing showing the results of measuring the element concentration of a metal substrate (SUS316L) immersed in an aqueous sulfuric acid solution at 80 ° C. and pH 4 for 100 hours using Auger electron spectroscopy. It can be seen that in addition to the constituent elements (Fe, Cr, Ni) of the metal substrate, oxygen (O ′) derived from the surface oxide is present at a depth of about 10 nm from the surface layer. Therefore, under such conditions, the average particle diameter of the conductive particles is preferably 10 nm or more, more preferably 10 nm to 100 nm, and even more preferably 10 nm to 20 nm. In addition, since the acidic atmosphere in a battery changes with electric power generation conditions, it is desirable to perform the prior evaluation of the thickness of a surface oxide on the conditions which simulated the internal environment in a battery according to electric power generation conditions.
　代表的な金属基材材料に形成される酸化被膜の厚さは、ＳＵＳでは０．００１ｎｍ～０．１ｎｍ程度、Ａｌでは０．００１ｎｍ～１ｎｍ程度である。したがって、導電性粒子の平均粒子径は、好ましくは０．０１ｎｍ～１００ｎｍであり、より好ましくは１ｎｍ～１００ｎｍであり、さらに好ましくは１０ｎｍ～１００ｎｍである。０．０１ｎｍ以上であれば本実施形態の効果が得られるが、特に、１０ｎｍ以上であれば、ほぼ全ての基材金属又は中間層を構成する材料が形成する酸化被膜の厚さ以上となる。そのため導電性粒子同士や導電性粒子と金属基材及び中間層との間の接点が確保され、導電性が向上する。一方、１００ｎｍ以下であれば、粒子間に多数の接点を確保でき、かつ粒子間の空隙を小さくすることができるため、密着性及び導電性が向上する。なお、ここでの「粒子径」とは、粒子の輪郭線上の任意の２点間の距離のうち、最大の距離を意味するものとする。また「平均粒子径」の値としては、特に言及のない限り、走査型電子顕微鏡（ＳＥＭ）や透過型電子顕微鏡（ＴＥＭ）などの観察手段を用い、数～数十視野中に観察される粒子の粒子径の平均値として算出される値を採用するものとする。 The thickness of the oxide film formed on a typical metal base material is about 0.001 nm to 0.1 nm for SUS and about 0.001 nm to 1 nm for Al. Therefore, the average particle diameter of the conductive particles is preferably 0.01 nm to 100 nm, more preferably 1 nm to 100 nm, and further preferably 10 nm to 100 nm. If the thickness is 0.01 nm or more, the effect of the present embodiment can be obtained. However, if the thickness is 10 nm or more, the thickness of the oxide film formed by almost all the base metal or the material constituting the intermediate layer is increased. Therefore, the contact between the conductive particles or between the conductive particles and the metal substrate and the intermediate layer is secured, and the conductivity is improved. On the other hand, when the thickness is 100 nm or less, a large number of contacts can be ensured between the particles, and voids between the particles can be reduced, so that adhesion and conductivity are improved. Here, the “particle diameter” means the maximum distance among the distances between any two points on the particle outline. Further, as the value of “average particle diameter”, unless otherwise specified, particles observed in several to several tens of fields using an observation means such as a scanning electron microscope (SEM) or a transmission electron microscope (TEM) The value calculated as the average value of the particle diameters of the particles shall be adopted.
　導電性粒子による金属基材の被覆率は、好ましくは５０％以上１００％以下、より好ましくは６５％以上１００％以下、さらに好ましくは７０％以上１００％以下、特に好ましくは８０％以上９５％以下である。５０％以上であれば、十分な導電性を確保でき、導電部材の接触抵抗の上昇を抑制できる。導電性向上の観点では、被覆率は大きいほど好ましく、１００％（完全被覆）であることが好ましい。ただし、被覆率が大きいほど導電性粒子の量は増加する。代表的な導電性粒子である貴金属元素は高価であるため、コスト面を考慮すると、導電性が確保される限り被覆率が小さいほうが好ましい。なお、「導電性粒子による金属基材の被覆率」とは、導電部材（セパレータ５）を積層方向から見た場合、金属基材２５２と重複する導電性補強層内の導電粒子の面積の割合を意味するものとする。被覆率は、例えば、オージェ電子分光法により得られた導電性粒子の元素の面内分布を画像処理することによって、その面積比から被覆率（基材露出率）を算出すれば良い。 The coverage of the metal substrate with the conductive particles is preferably 50% to 100%, more preferably 65% to 100%, still more preferably 70% to 100%, and particularly preferably 80% to 95%. It is. If it is 50% or more, sufficient electroconductivity can be ensured and the raise of the contact resistance of an electroconductive member can be suppressed. From the viewpoint of improving conductivity, the coverage is preferably as large as possible, and is preferably 100% (complete coverage). However, the amount of conductive particles increases as the coverage increases. Since noble metal elements which are typical conductive particles are expensive, considering the cost, it is preferable that the coverage is small as long as conductivity is ensured. The “covering ratio of the metal substrate with the conductive particles” means the ratio of the area of the conductive particles in the conductive reinforcing layer overlapping the metal substrate 252 when the conductive member (separator 5) is viewed from the stacking direction. Means. For the coverage, for example, the in-plane distribution of elements of conductive particles obtained by Auger electron spectroscopy may be image-processed, and the coverage (base material exposure rate) may be calculated from the area ratio.
　図２７は、酸化被膜を形成させた金属基材の表面に導電性粒子（Ａｕ）を被覆させた部材における、導電性粒子による金属基材の被覆率と接触抵抗との関係を示している。図２７における点線で示したグラフは、金属基材表面の酸化皮膜が多く、緻密な状態における被覆率と接触抵抗との関係を示し、実線で示したグラフは、酸化皮膜が少ない状態における被覆率と接触抵抗との関係を示す。図２７から被覆率が減少すると接触抵抗は増加する傾向にあることが分かる。さらに、酸化被膜の密度によっても異なるが、被覆率５０％以上であれば酸化被膜の状態が異なっていても接触抵抗が有意に低減できることが確認される。 FIG. 27 shows the relationship between the coverage of the metal substrate by the conductive particles and the contact resistance in the member in which the surface of the metal substrate on which the oxide film is formed is coated with the conductive particles (Au). The graph shown by the dotted line in FIG. 27 shows the relationship between the coverage and the contact resistance in a dense state with a lot of oxide film on the surface of the metal substrate, and the graph shown by the solid line shows the coverage in a state with little oxide film. And the contact resistance. It can be seen from FIG. 27 that the contact resistance tends to increase as the coverage decreases. Furthermore, although depending on the density of the oxide film, it is confirmed that the contact resistance can be significantly reduced even if the state of the oxide film is different if the coverage is 50% or more.
　導電性補強層は、導電性粒子に加えてその他の材料を含んでいても良い。その他の材料を含むことにより、層間の導電性向上のみならず、耐食性にも優れる。また、導電性粒子として高価な貴金属元素を用いた場合に、その使用量を低減でき、コスト面で有利である。その他の材料としては、周期律表の第４族の金属（Ｔｉ、Ｚｒ、Ｈｆ）、第５族の金属（Ｖ、Ｎｂ、Ｔａ）、第６族の金属（Ｃｒ、Ｍｏ、Ｗ）などの金属；Ｓｉ及びＢ等の半金属；上記金属の合金、炭化物及び窒化物などが挙げられる。これらのうち、クロム（Ｃｒ）、タングステン（Ｗ）、チタン（Ｔｉ）、モリブデン（Ｍｏ）、ニオブ（Ｎｂ）もしくはハフニウム（Ｈｆ）といったイオン溶出の少ない金属、又はこれらの窒化物、炭化物もしくは炭窒化物が好ましく用いられる。より好ましくは、ＣｒもしくはＴｉ、又はこれらの炭化物もしくは窒化物が用いられる。特に、上述したイオン溶出の少ない金属又はその炭化物もしくは窒化物を用いた場合、導電部材の耐食性を有意に向上させることができる。 The conductive reinforcing layer may contain other materials in addition to the conductive particles. By including other materials, not only the conductivity between layers is improved, but also the corrosion resistance is excellent. Further, when an expensive noble metal element is used as the conductive particles, the amount used can be reduced, which is advantageous in terms of cost. Other materials include Group 4 metals (Ti, Zr, Hf), Group 5 metals (V, Nb, Ta), Group 6 metals (Cr, Mo, W), etc. Metals; semimetals such as Si and B; alloys, carbides and nitrides of the above metals. Among these, metals with low ion elution such as chromium (Cr), tungsten (W), titanium (Ti), molybdenum (Mo), niobium (Nb) or hafnium (Hf), or nitrides, carbides or carbonitrides thereof. The product is preferably used. More preferably, Cr or Ti, or a carbide or nitride thereof is used. In particular, when the above-described metal with little ion elution or a carbide or nitride thereof is used, the corrosion resistance of the conductive member can be significantly improved.
　導電性補強層２５５における導電性粒子の含有率は特に制限されず、導電性粒子による金属基材の被覆率が上記所望の値となるように適宜調整すれば良い。 The content of the conductive particles in the conductive reinforcing layer 255 is not particularly limited, and may be appropriately adjusted so that the coverage of the metal substrate with the conductive particles becomes the above desired value.
　ここで、導電性粒子以外の導電性補強層を構成する材料は、下記に詳述する中間層を構成する材料（中間層を構成する金属、金属の炭化物又は金属の窒化物）の熱膨張率以上であることが好ましく、該熱膨張率を超えることがより好ましい。一般的に、導電性炭素層は熱膨張しにくく、金属基材は熱膨張しやすい。このため、上記したような熱膨張率となるように、導電性補強層及び中間層を構成する材料を選択することにより、金属基材、導電性補強層、中間層及び導電性薄膜層各層の熱による膨張収縮の差を抑制して、各層の剥離などを防止できる。また、このような場合には、導電性補強層と中間層との密着性を向上することもできる。 Here, the material constituting the conductive reinforcing layer other than the conductive particles is the thermal expansion coefficient of the material constituting the intermediate layer (metal, metal carbide or metal nitride constituting the intermediate layer) described in detail below. It is preferable that the thermal expansion coefficient be exceeded. In general, the conductive carbon layer is difficult to thermally expand, and the metal substrate is easily thermally expanded. For this reason, the metal base material, the conductive reinforcing layer, the intermediate layer, and the conductive thin film layer are selected by selecting the materials constituting the conductive reinforcing layer and the intermediate layer so that the thermal expansion coefficient is as described above. A difference in expansion and contraction due to heat can be suppressed, and peeling of each layer can be prevented. In such a case, the adhesion between the conductive reinforcing layer and the intermediate layer can also be improved.
　また、本実施形態において、導電性補強層における導電性粒子の金属基材に対する被覆率は、ガス流れ方向の上流から下流に向かって増大することが好ましい。具体的には、導電性粒子の被覆率は、アノード及びカソードによらず上流が最も低く５０％程度とし、腐食環境の厳しい下流は、発電条件等を鑑みて必要に応じて被覆率を増加させるのが好ましい。なお、かかる導電性補強層の面内方向における濃度勾配は、ガス流れ方向に対して連続的に増加する形態であっても良い。また、前記濃度勾配は、異なる濃度を有する複数の分割領域を設けることにより段階的に増加する形態であっても良い。ただし、導電性粒子は全領域にわたって均一に分散されていても良い。 Moreover, in this embodiment, it is preferable that the coverage of the conductive particles in the conductive reinforcing layer with respect to the metal substrate increases from the upstream to the downstream in the gas flow direction. Specifically, the coverage of the conductive particles is the lowest at the upstream regardless of the anode and cathode, and is about 50%, and the downstream of the severe corrosive environment increases the coverage as necessary in consideration of power generation conditions and the like. Is preferred. Note that the concentration gradient in the in-plane direction of the conductive reinforcing layer may continuously increase with respect to the gas flow direction. Further, the density gradient may be increased stepwise by providing a plurality of divided regions having different densities. However, the conductive particles may be uniformly dispersed over the entire region.
　導電性補強層における導電性粒子の分散形態は、導電部材の導電性が確保される限り特に制限されない。図２８は、本実施形態に係る導電性粒子及び柱状性材料含む導電部材の模式断面図である。なお、上記「柱状性材料」とは、結晶配向性の高い柱状組織を有する材料をいう。また、「結晶配向性」は、第二実施形態における緻密バリア層の欄で説明したものと同様である。 The dispersion form of the conductive particles in the conductive reinforcing layer is not particularly limited as long as the conductivity of the conductive member is ensured. FIG. 28 is a schematic cross-sectional view of a conductive member including conductive particles and a columnar material according to the present embodiment. The “columnar material” refers to a material having a columnar structure with high crystal orientation. “Crystal orientation” is the same as that described in the dense barrier layer column in the second embodiment.
　本実施形態において、導電性補強層２５５は、導電性粒子２５７に加えて、導電部材の厚さ方向に多数配置した柱状組織を有する柱状性材料２５８を含む。そして、前記導電性粒子２５７は導電性補強層の柱状性材料２５８の表面及び金属基材２５２と導電性補強層２５５との間の界面に存在する。 In this embodiment, the conductive reinforcing layer 255 includes a columnar material 258 having a columnar structure arranged in the thickness direction of the conductive member in addition to the conductive particles 257. The conductive particles 257 are present on the surface of the columnar material 258 of the conductive reinforcing layer and on the interface between the metal substrate 252 and the conductive reinforcing layer 255.
　導電性補強層がナノレベルで多数の柱状組織を有する柱状性材料を含む場合、柱状組織の間の空隙が酸性水の流路となり、柱状組織の表面及び基材金属表面において酸化皮膜が形成されやすい。特に、後述する中間層が導電部材の厚さ方向に多数配置した柱状組織を有する柱状性材料から構成される場合、柱状間の隙間が酸性水の通路となり、酸化被膜の形成が進行しやすい。そして、そのような酸化被膜は絶縁性を示すため、セパレータの導電性を低下させ、セパレータとしての接触抵抗が増大するという問題があった。本実施形態の導電性補強層においては、柱状性材料の表面に導電性粒子が存在するため、柱状間の導電パスが形成され、面内方向の導電性を十分に確保することができる。さらに、本実施形態においては、金属基材と導電性補強層との間の界面にも導電性粒子が存在するため、金属基材界面での抵抗増加を抑制することができる。したがって、酸化被膜が形成された場合であっても、導電性の低下を効果的に抑制することができる。そのような柱状性材料は、スパッタリング法を用いて成膜した場合に、生成されやすい。 When the conductive reinforcing layer includes a columnar material having a large number of columnar structures at the nano level, voids between the columnar structures become a flow path of acidic water, and an oxide film is formed on the surface of the columnar structure and the surface of the base metal. Cheap. In particular, when an intermediate layer, which will be described later, is made of a columnar material having a columnar structure arranged in the thickness direction of the conductive member, the gap between the columns forms a passage for acidic water, and the formation of an oxide film tends to proceed. And since such an oxide film shows insulation, there existed a problem that the electroconductivity of a separator was reduced and the contact resistance as a separator increased. In the conductive reinforcing layer of this embodiment, since conductive particles are present on the surface of the columnar material, a conductive path between the columnar shapes is formed, and sufficient in-plane conductivity can be secured. Furthermore, in this embodiment, since conductive particles exist also at the interface between the metal substrate and the conductive reinforcing layer, an increase in resistance at the metal substrate interface can be suppressed. Therefore, even if an oxide film is formed, a decrease in conductivity can be effectively suppressed. Such a columnar material is easily generated when a film is formed using a sputtering method.
　なお、本実施形態において、導電性補強層及び中間層は導電部材の厚さ方向に多数配置した柱状組織を有するが、中間層の構造は柱状構造に限定されるわけではなく、他の多様な形態をとることができる。また、導電性粒子の分散形態は上記の形態に制限されるわけではなく、他の分散形態も好適に用いることができる。他の分散形態としては、例えば、導電性粒子及びその他の材料がそれぞれ層を形成して積層された構造であっても良い。そのような導電性補強層や中間層の構造は、ＳＥＭ－ＥＤＸ（走査型電子顕微鏡－エネルギー分散型Ｘ線分析装置）又はＴＥＭ等によって確認することができる。 In the present embodiment, the conductive reinforcing layer and the intermediate layer have a columnar structure arranged in a large number in the thickness direction of the conductive member. However, the structure of the intermediate layer is not limited to the columnar structure, and various other types. Can take form. Moreover, the dispersion | distribution form of electroconductive particle is not necessarily restricted to said form, The other dispersion | distribution form can also be used suitably. As another dispersion form, for example, a structure in which conductive particles and other materials are laminated by forming layers may be used. The structure of such a conductive reinforcing layer or intermediate layer can be confirmed by SEM-EDX (scanning electron microscope-energy dispersive X-ray analyzer), TEM, or the like.
　導電性補強層２５５の厚さは特に限定されず、金属基材の界面等における酸化皮膜の形成による抵抗増加を抑制できる限り、薄い方が好ましい。具体的には、金属基材及び中間層を有する導電部材において、金属基材の表面に酸化被膜が形成される領域の厚さ以上であることが好ましい。また、導電性補強層２５５の厚さは、後述する中間層の厚さよりも薄い方が好ましい。この場合には、中間層の密着性向上の効果及び導電性補強層の導電性向上の効果が発揮されるとともに、省スペース化が可能である。 The thickness of the conductive reinforcing layer 255 is not particularly limited, and the thinner one is preferable as long as an increase in resistance due to the formation of an oxide film at the interface of the metal substrate can be suppressed. Specifically, in a conductive member having a metal substrate and an intermediate layer, the thickness is preferably equal to or greater than the thickness of a region where an oxide film is formed on the surface of the metal substrate. The thickness of the conductive reinforcing layer 255 is preferably thinner than the thickness of the intermediate layer described later. In this case, the effect of improving the adhesion of the intermediate layer and the effect of improving the conductivity of the conductive reinforcing layer are exhibited, and space saving is possible.
　導電性補強層は、金属基材の少なくとも一方の表面上に存在すればよいが、本実施形態における所望の効果を一層高く発揮する観点から、金属基材の両面に存在しても良い。なお、導電性補強層が金属基材の両面上に存在する場合には、それぞれの導電性補強層の表面上に中間層及び導電性炭素層がさらに設けられることとなる。金属基材の表面の一方のみに導電性補強層が存在する場合には、当該導電性補強層は、ＭＥＡ側に配置されることとなる導電性炭素層と金属基材との間に存在することが好ましい。また、導電性補強層は１層だけでなく、複数の層からなる積層構造を有していても良い。 The conductive reinforcing layer may be present on at least one surface of the metal base material, but may be present on both surfaces of the metal base material from the viewpoint of further achieving the desired effect in the present embodiment. In addition, when a conductive reinforcement layer exists on both surfaces of a metal base material, an intermediate | middle layer and a conductive carbon layer will be further provided on the surface of each conductive reinforcement layer. When a conductive reinforcing layer exists only on one of the surfaces of the metal substrate, the conductive reinforcing layer exists between the conductive carbon layer to be disposed on the MEA side and the metal substrate. It is preferable. Further, the conductive reinforcing layer may have a laminated structure including not only one layer but also a plurality of layers.
　［中間層］
　中間層２５６は、導電性補強層２５５上に配置される層であり、金属基材２５２と導電性補強層２５５との密着性を向上させるという機能や、金属基材２５２からのイオンの溶出を防止するという機能を有する。特に、中間層２５６の設置による作用効果は、導電性補強層２５５が上記金属又はその合金から構成される場合に顕著に発現する。また、下記に詳述するが、導電性炭素層２５４が導電性炭素を含み、かつ、ラマン散乱分光分析により測定されたＤバンドピーク強度（ＩＤ）とＧバンドピーク強度（ＩＧ）との強度比Ｒ（ＩＤ／ＩＧ）が大きい（例えば、Ｒ値が２．０を超える）場合には、中間層２５６を設けることにより導電性補強層２５５との密着性効果が顕著に発現する。 [Middle layer]
The intermediate layer 256 is a layer disposed on the conductive reinforcement layer 255, and improves the adhesion between the metal substrate 252 and the conductive reinforcement layer 255, and the elution of ions from the metal substrate 252. It has a function of preventing. In particular, the effect of the installation of the intermediate layer 256 is remarkably exhibited when the conductive reinforcing layer 255 is made of the above metal or an alloy thereof. As will be described in detail below, the conductive carbon layer 254 contains conductive carbon, and the D band peak intensity (I D ) and G band peak intensity (I G ) measured by Raman scattering spectroscopic analysis. When the intensity ratio R (I D / I G ) is large (for example, the R value exceeds 2.0), the adhesive effect with the conductive reinforcing layer 255 is remarkably exhibited by providing the intermediate layer 256. .
　中間層２５６を構成する材料としては、上記の密着性を付与するものであれば特に制限はないが、第一実施形態の中間層３２と同様の材料を使用することができる。また、中間層２５６の厚さは特に制限されないが、第一実施形態の中間層３２と同様の厚さとすることができる。さらに、中間層２５６の構造も特に制限されないが、第一実施形態の中間層３２と同様の柱状構造とすることができる。 The material constituting the intermediate layer 256 is not particularly limited as long as it provides the above-mentioned adhesion, but the same material as that of the intermediate layer 32 of the first embodiment can be used. The thickness of the intermediate layer 256 is not particularly limited, but can be the same thickness as the intermediate layer 32 of the first embodiment. Further, the structure of the intermediate layer 256 is not particularly limited, but can be a columnar structure similar to the intermediate layer 32 of the first embodiment.
　上述したように、中間層２５６を構成する材料の熱膨張率が、導電性補強層２５５を構成する材料の熱膨張率以下であると、中間層と導電性補強層との密着性などを向上することができる。また、中間層２５６の熱膨張率が導電性炭素層２５４の熱膨張率と同等又はそれ以上であると、中間層２５６と導電性補強層２５５との密着性を向上することができる。これらを考慮して、金属基材を構成する材料の熱膨張率（αｓｕｂ）、導電性補強層を構成する材料の熱膨張率（αｒｅｉ）、中間層を構成する材料の熱膨張率（αｍｉｄ）、及び導電性薄膜層を構成する材料の熱膨張率（αｃ）は、下記関係を満足することが好ましい。 As described above, when the thermal expansion coefficient of the material constituting the intermediate layer 256 is equal to or lower than the thermal expansion coefficient of the material constituting the conductive reinforcing layer 255, the adhesion between the intermediate layer and the conductive reinforcing layer is improved. can do. Further, when the thermal expansion coefficient of the intermediate layer 256 is equal to or higher than the thermal expansion coefficient of the conductive carbon layer 254, adhesion between the intermediate layer 256 and the conductive reinforcing layer 255 can be improved. In consideration of these, the coefficient of thermal expansion (α sub ) of the material constituting the metal substrate, the coefficient of thermal expansion (α rei ) of the material constituting the conductive reinforcing layer, and the coefficient of thermal expansion of the material constituting the intermediate layer ( α mid ) and the coefficient of thermal expansion (α c ) of the material constituting the conductive thin film layer preferably satisfy the following relationship.
［数４］
αｓｕｂ ≧ αｒｅｉ ≧ αｍｉｄ ≧ αｃ [Equation 4]
α sub ≧ α rei ≧ α mid ≧ α c
　［導電性炭素層］
　導電性炭素層２５４は、中間層２５６上に配置され、導電性炭素を含む層である。この層の存在によって、導電部材（セパレータ）５の導電性を確保しつつ、金属基材２５２のみの場合と比較して耐食性が改善される。このような導電性炭素層２５４としては、第一実施形態の導電性炭素層３３を使用することができる。 [Conductive carbon layer]
The conductive carbon layer 254 is a layer that is disposed on the intermediate layer 256 and contains conductive carbon. By the presence of this layer, the corrosion resistance is improved as compared with the case of only the metal substrate 252 while ensuring the conductivity of the conductive member (separator) 5. As such a conductive carbon layer 254, the conductive carbon layer 33 of the first embodiment can be used.
　次に、導電部材を製造するための好ましい実施形態を記載するが、本発明の技術的範囲は下記の形態のみには限定されない。また、セパレータ５Ｂを構成する導電部材の各構成要素の材質などの諸条件については、上述した通りであるため、ここでは説明を省略する。 Next, a preferred embodiment for manufacturing a conductive member will be described, but the technical scope of the present invention is not limited to the following embodiment. Moreover, since various conditions such as the material of each component of the conductive member constituting the separator 5B are as described above, description thereof is omitted here.
　まず、金属基材として、所望の厚さのステンレス板などを準備する。次いで、第一実施形態と同様に、適当な溶媒を用いて、準備した金属基材の表面の脱脂及び洗浄処理を行う。続いて、金属基材の表面（両面）に形成されている酸化皮膜の除去を行う。酸化皮膜を除去するための手法としては、第一実施形態と同様の方法で行う。 First, a stainless steel plate having a desired thickness is prepared as a metal substrate. Next, as in the first embodiment, the surface of the prepared metal substrate is degreased and cleaned using an appropriate solvent. Subsequently, the oxide film formed on the surface (both sides) of the metal substrate is removed. As a method for removing the oxide film, the same method as in the first embodiment is used.
　次に、上記の処理を施した金属基材の表面に、導電性補強層を成膜する工程を行う。例えば、上述した導電性補強層の構成材料（導電性粒子及び必要に応じてその他の材料）をターゲットとして、金属基材上に導電性粒子を含む層を原子レベルで積層することにより、導電性補強層を形成することができる。これにより、直接付着した導電性補強層と金属基材との界面及びその近傍は、分子間力等によって長期間にわたって密着性が保持される。 Next, a step of forming a conductive reinforcing layer on the surface of the metal substrate subjected to the above-described treatment is performed. For example, by using the above-described constituent material of the conductive reinforcing layer (conductive particles and other materials as necessary) as a target, a layer containing conductive particles is laminated on a metal substrate at the atomic level, thereby providing conductivity. A reinforcing layer can be formed. As a result, the adhesion between the directly adhered conductive reinforcing layer and the metal substrate and the vicinity thereof is maintained for a long period of time by intermolecular force or the like.
　導電性粒子及びその他の材料を積層するのに好適な手法としては、メッキ法、スパッタリング法もしくはイオンプレーティング法などのＰＶＤ法、又はＦＣＶＡ法などのイオンビーム蒸着法などが挙げられる。スパッタリング法としては、マグネトロンスパッタリング法、ＵＢＭＳ法、デュアルマグネトロンスパッタ法などが挙げられる。また、イオンプレーティング法としては、アークイオンプレーティング法などが挙げられる。なかでも、スパッタリング法及びイオンプレーティング法を用いることが好ましく、スパッタリング法を用いることが特に好ましい。そのような手法によれば、比較的低温で成膜が可能であり、下地である金属基材へのダメージを最小限に抑えることができる。また、スパッタリング法によれば、バイアス電圧等を制御することで、成膜される層の膜質をコントロールできる。さらに、スパッタリング法では、スパッタリングレートなどのスパッタ条件を調節することで、導電性粒子の分散形態を制御することができる。スパッタリング法の中でも、特に、アンバランスドマグネトロンスパッタリング法を用いることが好ましい。かかる手法によれば、金属基材と中間層と間の密着性に優れる導電性補強層を形成することができる。 Suitable methods for laminating the conductive particles and other materials include PVD methods such as a plating method, sputtering method or ion plating method, or ion beam evaporation methods such as FCVA method. Examples of the sputtering method include magnetron sputtering, UBMS, and dual magnetron sputtering. Examples of the ion plating method include an arc ion plating method. Especially, it is preferable to use sputtering method and an ion plating method, and it is especially preferable to use sputtering method. According to such a method, film formation can be performed at a relatively low temperature, and damage to the metal base material as a base can be minimized. In addition, according to the sputtering method, the film quality of the deposited layer can be controlled by controlling the bias voltage and the like. Further, in the sputtering method, the dispersion form of the conductive particles can be controlled by adjusting the sputtering conditions such as the sputtering rate. Among the sputtering methods, it is particularly preferable to use an unbalanced magnetron sputtering method. According to this method, a conductive reinforcing layer having excellent adhesion between the metal substrate and the intermediate layer can be formed.
　また、導電性粒子の被覆率や粒子径は、スパッタ時間と分散量との関係を予め把握した上で、これらを制御することにより所望の範囲に設定することができる。 Further, the coverage and particle diameter of the conductive particles can be set to a desired range by controlling the relationship between the sputtering time and the dispersion amount in advance.
　続いて、上記導電性補強層の表面に中間層及び導電性炭素層を成膜する工程を行う。この際、中間層及び導電性炭素層を成膜する手法としては、導電性補強層の成膜について上述したのと同様の手法を用いることができ、好ましくは、スパッタリング法及びイオンプレーティング法を用い、より好ましくはスパッタリング法を用い、特に好ましくはアンバランスドマグネトロンスパッタリング法を用いる。ただし、ターゲットを中間層及び導電性炭素層の構成材料に変更する必要がある。中間層をかかる方法で形成させた場合には、密着性をより向上させることができる。また、そのような手法で導電性炭素層を形成させた場合には、上述した利点に加えて、水素含有量の少ない炭素層を形成することができる。その結果、炭素原子同士の結合（ｓｐ２混成炭素）の割合を増加させることができ、優れた導電性を達成することができる。 Subsequently, a step of forming an intermediate layer and a conductive carbon layer on the surface of the conductive reinforcing layer is performed. At this time, as a method for forming the intermediate layer and the conductive carbon layer, the same method as described above for the formation of the conductive reinforcing layer can be used. Preferably, a sputtering method and an ion plating method are used. More preferably, a sputtering method is used, and an unbalanced magnetron sputtering method is particularly preferably used. However, it is necessary to change the target to the constituent material of the intermediate layer and the conductive carbon layer. When the intermediate layer is formed by such a method, the adhesion can be further improved. Further, when the conductive carbon layer is formed by such a method, in addition to the above-described advantages, a carbon layer having a low hydrogen content can be formed. As a result, the ratio of bonds between carbon atoms (sp 2 hybrid carbon) can be increased, and excellent conductivity can be achieved.
　また、中間層をスパッタリング法やイオンプレーティング法で導電性補強層上に形成する場合には、導電性補強層と中間層との境界部分は、導電性補強層由来の部分と、中間層由来の部分とが、共存するような構造となっている場合がある。このような共存部分が存在したとしても、導電性補強層及び中間層が上記したような厚みで配置されていれば、本発明による効果は十分達成できる。 When the intermediate layer is formed on the conductive reinforcing layer by sputtering or ion plating, the boundary between the conductive reinforcing layer and the intermediate layer is derived from the conductive reinforcing layer and the intermediate layer. May have a structure that coexists. Even if such a coexistence portion exists, the effect of the present invention can be sufficiently achieved if the conductive reinforcing layer and the intermediate layer are arranged with the above-described thickness.
　なお、各層の成膜をスパッタリング法により行う場合には、スパッタリング時に金属基材に対して負のバイアス電圧を印加すると良い。この場合、イオン照射効果によって、各層の構成粒子やグラファイトクラスタが緻密に集合した構造の層を成膜することができる。このような層は優れた導電性を発揮することから、他の部材（例えば、ＭＥＡ）との接触抵抗の小さい導電部材（セパレータ）を提供することができる。なお、印加される負のバイアス電圧の大きさ（絶対値）は特に制限されず、各層を成膜可能な電圧が採用される。印加される電圧の大きさは、好ましくは５０～５００Ｖであり、より好ましくは１００～３００Ｖである。なお、成膜時のその他の条件等の具体的な形態は特に制限されず、従来公知の知見が適宜参照される。 In addition, when forming each layer by sputtering method, it is good to apply a negative bias voltage with respect to a metal base material at the time of sputtering. In this case, a layer having a structure in which constituent particles and graphite clusters of each layer are densely assembled can be formed by the ion irradiation effect. Since such a layer exhibits excellent conductivity, it is possible to provide a conductive member (separator) having a low contact resistance with another member (for example, MEA). The magnitude (absolute value) of the negative bias voltage to be applied is not particularly limited, and a voltage capable of forming each layer is adopted. The magnitude of the applied voltage is preferably 50 to 500V, more preferably 100 to 300V. In addition, specific forms, such as other conditions at the time of film-forming, are not restrict | limited, A conventionally well-known knowledge is referred suitably.
　上述した手法によれば、金属基材２５２の一方の主表面に導電性補強層２５５、中間層２５６、及び導電性炭素層２５４が形成された導電部材を製造することができる。そして、金属基材２５２の両面に導電性補強層２５５が形成された導電部材を製造するには、金属基材２５２の他方の主表面に対して、上述したのと同様の手法によって、導電性補強層２５５を形成すれば良い。 According to the above-described method, a conductive member in which the conductive reinforcing layer 255, the intermediate layer 256, and the conductive carbon layer 254 are formed on one main surface of the metal base 252 can be manufactured. And in order to manufacture the electrically-conductive member in which the electroconductive reinforcement layer 255 was formed in both surfaces of the metal base material 252, it is electroconductive by the method similar to the above-mentioned with respect to the other main surface of the metal base material 252. The reinforcing layer 255 may be formed.
　本実施形態の導電部材は、第一実施形態と同様に、種々の用途に用いることができる。その代表例が図１に示すＰＥＦＣのセパレータ５Ｂである。本実施形態の導電部材をＰＥＦＣのセパレータに使用する場合、上記導電部材は、アノードセパレータ５ａ及びカソードセパレータ５ｃの少なくとも一方に適用されていれば良い。しかし、特にカソード側で水が多量に生成することなどを考慮すると、上記導電部材を少なくともカソードセパレータとして使用することが好ましい。より好ましくは、上記導電部材を、カソードセパレータ及びアノードセパレータの両方に使用する。また、アノードセパレータ５ａ及びカソードセパレータ５ｃの両方に上記導電部材が設けられている場合には、導電性補強層における導電性粒子の量がアノードセパレータよりもカソードセパレータの方が大きいことが好ましい。燃料電池では、カソードで、０～１Ｖ（ｖｓ　ＳＨＥ）の電圧が発生し、セパレータの表面にもほぼ同等の電位がかかる。さらに、カソード側では発電によって生成した水が多量に存在するため、極めて腐食環境が厳しい状態にある。よって、耐食性がより要求されるカソードセパレータにおいて、導電性粒子による導電性・耐食性向上の効果が一層発揮される。 The conductive member of the present embodiment can be used for various applications as in the first embodiment. A typical example is a PEFC separator 5B shown in FIG. When the conductive member of this embodiment is used for a PEFC separator, the conductive member may be applied to at least one of the anode separator 5a and the cathode separator 5c. However, considering the generation of a large amount of water on the cathode side, it is preferable to use the conductive member as at least a cathode separator. More preferably, the conductive member is used for both the cathode separator and the anode separator. Further, when the conductive member is provided in both the anode separator 5a and the cathode separator 5c, the amount of conductive particles in the conductive reinforcing layer is preferably larger in the cathode separator than in the anode separator. In a fuel cell, a voltage of 0 to 1 V (vs. SHE) is generated at the cathode, and a substantially equal potential is also applied to the surface of the separator. Furthermore, since a large amount of water generated by power generation exists on the cathode side, the corrosive environment is extremely severe. Therefore, in the cathode separator that requires more corrosion resistance, the effect of improving the conductivity and corrosion resistance due to the conductive particles is further exhibited.
　なお、上記では、本実施形態の導電部材を、ＰＥＦＣのセパレータに適用することについて説明してきたが、本実施形態の導電部材の用途はこれに限られない。例えば、第一実施形態の導電部材と同様に、ＰＥＦＣ以外にも、ＰＡＦＣ、ＭＣＦＣ、ＳＯＦＣ又はＡＦＣなどの各種の燃料電池用セパレータとしても使用可能である。また、燃料電池用セパレータ以外にも、導電性・耐食性の両立が求められている各種の用途に用いられる。本実施形態の導電部材が用いられる燃料電池用セパレータ以外の用途としては、例えば、他の燃料電池部品（集電板、バスバー、ガス拡散基体、ＭＥＡ）、電子部品の接点などが挙げられる。さらに、本実施形態の導電部材は、湿潤環境及び通電環境の下で使用することができる。そのような環境下で用いると、導電性及び耐食性の両立を図るという本発明の作用効果が顕著に発現する。 In the above description, the application of the conductive member of the present embodiment to a PEFC separator has been described. However, the application of the conductive member of the present embodiment is not limited to this. For example, like the conductive member of the first embodiment, in addition to PEFC, it can be used as various fuel cell separators such as PAFC, MCFC, SOFC, or AFC. In addition to the fuel cell separator, it is used in various applications that require both conductivity and corrosion resistance. Examples of uses other than the fuel cell separator in which the conductive member of the present embodiment is used include other fuel cell components (current collector plate, bus bar, gas diffusion base, MEA), contacts of electronic components, and the like. Furthermore, the conductive member of this embodiment can be used in a wet environment and an energized environment. When used in such an environment, the effect of the present invention of achieving both conductivity and corrosion resistance is remarkably exhibited.
　以下、本実施形態の導電部材の効果を、実施例及び参考例を用いて説明するが、本発明の技術的範囲はこれらの実施例に限定されない。 Hereinafter, the effects of the conductive member of the present embodiment will be described using examples and reference examples, but the technical scope of the present invention is not limited to these examples.
　［実施例III－１］
　導電部材を構成する金属基材として、ステンレス板（ＳＵＳ３１６Ｌ）を準備した。このステンレス板の厚さは１００μｍである。前処理として、このステンレス板を、エタノール液中で３分間超音波洗浄した。次いで、洗浄したステンレス板を真空チャンバ内に設置し、Ａｒガスによるイオンボンバード処理を行って、表面の酸化皮膜を除去した。なお、真空チャンバの真空度は１０－３Ｐａ程度とし、Ａｒガスの圧力は０．１～１Ｐａ程度とした。なお、上述した前処理及びイオンボンバード処理は、いずれもステンレス板の両面に対して行った。 [Example III-1]
A stainless steel plate (SUS316L) was prepared as a metal substrate constituting the conductive member. The stainless steel plate has a thickness of 100 μm. As a pretreatment, the stainless steel plate was ultrasonically cleaned in an ethanol solution for 3 minutes. Next, the cleaned stainless steel plate was placed in a vacuum chamber, and ion bombardment with Ar gas was performed to remove the oxide film on the surface. The vacuum degree of the vacuum chamber was about 10 −3 Pa, and the Ar gas pressure was about 0.1 to 1 Pa. The pretreatment and ion bombardment described above were both performed on both surfaces of the stainless steel plate.
　次に、アンバランスドマグネトロンスパッタリング法により、導電性粒子であるＡｕ及びその他の導電性補強層材料であるＣｒをターゲットとして、ステンレス板の両面にＡｕ及びＣｒからなる導電性補強層を形成した。なお、この際、導電性補強層（Ａｕ粒子層）の厚みを２０ｎｍとした。 Next, a conductive reinforcing layer made of Au and Cr was formed on both surfaces of the stainless steel plate by using unbalanced magnetron sputtering as a target with Au as conductive particles and Cr as another conductive reinforcing layer material. At this time, the thickness of the conductive reinforcing layer (Au particle layer) was 20 nm.
　一般にスパッタリングにて成膜する場合、成膜層は多数の柱状構造を有した成膜材料の層を形成するが、本導電性補強層は、柱状構造をしたＣｒからなる層の表面及びステンレス板（金属基材）との界面にＡｕ粒子が分散していることが明らかになった。また、導電性補強層において、Ａｕ粒子の被覆率（表面被覆率）は９０％であった。なお、Ａｕ粒子の被覆率はＡＥＳの面分析と画像解析にて算出した。被覆率の算出は後述するＡＥＳならびに画像解析手法に従って行ったが、本算出にあたっては、別途作成した導電性炭素層の成膜開始直前で成膜処理を停止したサンプルを用いた。 In general, when a film is formed by sputtering, the film forming layer forms a layer of a film forming material having a number of columnar structures. The conductive reinforcing layer is formed of a surface of a layer of Cr having a columnar structure and a stainless steel plate. It was revealed that Au particles were dispersed at the interface with the (metal substrate). In the conductive reinforcing layer, the Au particle coverage (surface coverage) was 90%. The Au particle coverage was calculated by AES surface analysis and image analysis. The coverage was calculated according to AES and an image analysis method described later. In this calculation, a sample in which the film formation process was stopped immediately before the start of film formation of the conductive carbon layer prepared separately was used.
　導電粒子（Ａｕ）被覆率は、Ａｕと、同時に成膜するＣｒのスパッタ速度の違いによって決めることが可能である。本実施例の場合、よりスパッタ速度の速いＡｕが必要最小限に分散するように、ターゲットのサイズや位置を変えることが望ましい。さらに、ターゲットの条件が決められた場合は、成膜時間にて被覆率や層の厚さを一意的に決めることが可能である。 The conductive particle (Au) coverage can be determined by the difference in sputtering rate between Au and Cr formed simultaneously. In the case of the present embodiment, it is desirable to change the size and position of the target so that Au having a higher sputtering speed is dispersed to the minimum necessary. Furthermore, when the target conditions are determined, the coverage ratio and the layer thickness can be uniquely determined by the film formation time.
　続いて、ＵＢＭＳ法により、Ｃｒをターゲットとして、ステンレス板の両面の導電性補強層の上に、Ｃｒからなる柱状構造を有する中間層を形成した。なお、中間層を形成する際には、ステンレス板に対して５０Ｖの大きさの負のバイアス電圧を印加しながら行った。また、中間層の厚さは０．２μｍであった。 Subsequently, an intermediate layer having a columnar structure made of Cr was formed on the conductive reinforcing layers on both surfaces of the stainless steel plate using Cr as a target by the UBMS method. The intermediate layer was formed while applying a negative bias voltage of 50 V to the stainless steel plate. The intermediate layer had a thickness of 0.2 μm.
　さらに、ＵＢＭＳ法により、固体グラファイトをターゲットとして、ステンレス板の両面上に形成された中間層の上に導電性炭素層を形成した。これにより、サンプル（III－１）を作製した。なお、導電性炭素層を形成する際には、ステンレス板に対して１４０Ｖの大きさの負のバイアス電圧を印加しながら行った。また、導電性炭素層の厚さは０．２μｍであった。 Further, a conductive carbon layer was formed on the intermediate layer formed on both surfaces of the stainless steel plate by using the UBMS method with solid graphite as a target. This produced Sample (III-1). The conductive carbon layer was formed while applying a negative bias voltage of 140 V to the stainless steel plate. Moreover, the thickness of the conductive carbon layer was 0.2 μm.
　［実施例III－２］
　上記実施例III－１と同様の手法により、サンプル（III－２）を作製した。なお、成膜時間を調整することにより、Ａｕ被覆率が３８％である導電性補強層を形成した。 [Example III-2]
Sample (III-2) was produced in the same manner as in Example III-1. In addition, the electroconductive reinforcement layer whose Au coverage is 38% was formed by adjusting the film-forming time.
　［実施例III－３］
　導電性粒子としてＡｕの代わりにＡｇを用いた以外は上記実施例III－１と同様の手法により、サンプル（III－３）を作製した。実施例III－１、III－２と同様にＡｇの被覆率を計測したところ、８３％であった。 [Example III-3]
Sample (III-3) was produced in the same manner as in Example III-1, except that Ag was used instead of Au as the conductive particles. The Ag coverage was measured in the same manner as in Examples III-1 and III-2 and found to be 83%.
　［参考例III－１］
　導電性粒子を用いることなく、ステンレス板上に直接Ｃｒからなる中間層を形成したこと以外は、上述した実施例III－１と同様の手法により、サンプル（III－４）を作製した。この際、中間層の厚さが、実施例III－１における導電性補強層の厚さ及び中間層の厚さの合計と等しくなるようにした。 [Reference Example III-1]
Sample (III-4) was produced in the same manner as in Example III-1 described above, except that the intermediate layer made of Cr was directly formed on the stainless steel plate without using conductive particles. At this time, the thickness of the intermediate layer was made equal to the sum of the thickness of the conductive reinforcing layer and the thickness of the intermediate layer in Example III-1.
［評価：耐食性試験］
　上記実施例III－１～III－３及び参考例III－１で作製した導電部材について、耐久性試験を行った。具体的には、作製した導電部材について、作製直後の接触抵抗値と、導電部材をｐＨ４の硫酸水溶液中に８０℃で１００時間浸漬させた後の接触抵抗値とを測定した。次に、作製直後の接触抵抗値に対する抵抗値の増加量を求めた。なお、上記硫酸水溶液は、燃料電池においてセパレータが曝される環境を模擬したものである。また、一般的に、燃料電池運転時の温度が室温（２５℃）～７０℃であるため、試験温度を８０℃に設定した。接触抵抗増加量が低いほど、電池の耐久性が向上したことを意味する。なお、上記における接触抵抗は導電部材の積層方向における接触抵抗値を意味し、測定は第一実施形態で説明した方法で行った。接触抵抗値の測定結果を、下記の表４に示す。 [Evaluation: Corrosion resistance test]
Durability tests were conducted on the conductive members produced in Examples III-1 to III-3 and Reference Example III-1. Specifically, with respect to the produced conductive member, the contact resistance value immediately after production and the contact resistance value after the conductive member was immersed in a sulfuric acid aqueous solution of pH 4 at 80 ° C. for 100 hours were measured. Next, the amount of increase in resistance value with respect to the contact resistance value immediately after fabrication was determined. The sulfuric acid aqueous solution simulates the environment where the separator is exposed in the fuel cell. In general, since the temperature during operation of the fuel cell is room temperature (25 ° C.) to 70 ° C., the test temperature was set to 80 ° C. The lower the contact resistance increase, the better the durability of the battery. In addition, the contact resistance in the above means the contact resistance value in the lamination direction of the conductive member, and the measurement was performed by the method described in the first embodiment. The measurement results of the contact resistance value are shown in Table 4 below.
　［ＡＥＳ（オージェ電子分光法）による元素濃度プロファイル解析］
　耐食性試験を行う前の実施例III－１～III－３及び参考例III－１で作製したサンプル（III－１）～（III－４）について、導電部材の積層方向の元素濃度プロファイルをＡＥＳにより測定した。図２９に、耐食性試験を行う前のサンプル（III－１）に関する、導電性炭素層の表面からの深さ方向における元素分布を示す。耐久試験を行う前は、基材表面に酸素の分布は確認されず、酸化被膜が形成されていないことが確認される。また、サンプル（III－２）～（III－４）のＡＥＳ測定でも、同様に酸化被膜の形成は確認されなかった。 [Element concentration profile analysis by AES (Auger electron spectroscopy)]
For the samples (III-1) to (III-4) prepared in Examples III-1 to III-3 and Reference Example III-1 before the corrosion resistance test, the element concentration profile in the stacking direction of the conductive member was measured by AES. It was measured. FIG. 29 shows the element distribution in the depth direction from the surface of the conductive carbon layer for sample (III-1) before the corrosion resistance test. Before the endurance test, the distribution of oxygen is not confirmed on the substrate surface, and it is confirmed that an oxide film is not formed. Similarly, in the AES measurement of samples (III-2) to (III-4), formation of an oxide film was not confirmed.
　次に、耐久試験を行った後のサンプル（III－１）～（III－４）について、導電部材の積層方向の元素濃度プロファイルをＡＥＳにより測定した。図３０～３３に、耐食性試験を行った後のサンプル（III－１）～（III－４）に関する、導電性炭素層の表面からの深さ方向における元素分布を示す。図３０～３３からわかるように、金属基材（Ｆｅ、Ｎｉ）の表面からＣｒ層の中間領域にかけて酸素（Ｏ）が分布しており、酸化被膜が形成されることがわかる。そして、実施例III－１～III－３の導電部材（サンプル（III－１）～（III－３））においては、酸素の分布領域（酸化被膜）にＡｕ又はＡｇの導電性粒子が存在するが、参考例III－１（サンプル（III－４））の導電部材においては、これらの導電性粒子が存在しないことがわかる。 Next, for the samples (III-1) to (III-4) after the endurance test, the element concentration profile in the stacking direction of the conductive member was measured by AES. 30 to 33 show the element distributions in the depth direction from the surface of the conductive carbon layer for the samples (III-1) to (III-4) after the corrosion resistance test was performed. As can be seen from FIGS. 30 to 33, oxygen (O) is distributed from the surface of the metal substrate (Fe, Ni) to the intermediate region of the Cr layer, and an oxide film is formed. In the conductive members of Examples III-1 to III-3 (samples (III-1) to (III-3)), Au or Ag conductive particles are present in the oxygen distribution region (oxide film). However, it can be seen that these conductive particles are not present in the conductive member of Reference Example III-1 (sample (III-4)).
　また、導電部材の面内方向の元素濃度プロファイルをＡＥＳにより測定し、導電性粒子の元素の面内分布を画像処理することによって、その面積比から導電性粒子による金属基材の被覆率を算出した。表４に結果を示す。なお、上記ＡＥＳ測定は下記条件で行った。 In addition, the element concentration profile in the in-plane direction of the conductive member is measured by AES, and the in-plane distribution of the element of the conductive particles is image-processed to calculate the coverage of the metal substrate with the conductive particles from the area ratio. did. Table 4 shows the results. The AES measurement was performed under the following conditions.
　ＡＥＳ装置名：電界放射型オージェ電子分分光装置　ＰＨＩ製　Ｍｏｄｅｌ－６８０
　　　　　　　　データポイント数：２５６×２５６　電子線加速電圧：１０ｋＶ
　画像処理による被覆率算出：高速画像処理装置　カールツァイス製ＫＳ４００
　　　　　　　　　　　　　　デジタル画像に取り込み、ターゲット元素の面積比を算出。 AES equipment name: Field emission type Auger electron spectrometer PHI Model-680
Number of data points: 256 × 256 Electron beam acceleration voltage: 10 kV
Coverage calculation by image processing: High-speed image processing device KS400 manufactured by Carl Zeiss
Import into digital images and calculate area ratio of target elements.
　表４に示すように、各実施例の導電部材は、参考例と比べて接触抵抗が極めて小さい値に抑えられることが確認された。このことから、導電性補強層を有する導電部材は酸化被膜が形成された場合であっても、導電部材の厚み方向における抵抗値の増加を抑制できることが確認された。 As shown in Table 4, it was confirmed that the conductive member of each example can be suppressed to a very small value of contact resistance as compared with the reference example. From this, it was confirmed that the conductive member having the conductive reinforcing layer can suppress an increase in the resistance value in the thickness direction of the conductive member even when the oxide film is formed.
　さらに、被覆率が５０％以上である実施例III－１の導電部材（サンプル（III－１））は、被覆率が５０％未満である実施例III－２の導電部材（サンプル（III－２））に比べ、接触抵抗の増加量を低減できることが確認された。 Furthermore, the conductive member of Example III-1 (sample (III-1)) having a coverage of 50% or more is the conductive member of Example III-2 (sample (III-2) having a coverage of less than 50%. It was confirmed that the increase in contact resistance can be reduced compared to)).
Figure JPOXMLDOC01-appb-T000005
 　＊１）粒子径は、ＳＥＭで観察した場合に観察される粒子の平均径である。そのため、被覆率が５０％以上になると粒子が互いに接して層を成すことから、計測が困難となる。このため、導電粒子から形成された層の厚さを測定した。
Figure JPOXMLDOC01-appb-T000005
 * 1) The particle diameter is an average particle diameter observed when observed by SEM. Therefore, when the coverage is 50% or more, the particles come into contact with each other to form a layer, which makes measurement difficult. For this reason, the thickness of the layer formed from the conductive particles was measured.
［第四実施形態］
　次に、本発明の第四実施形態に係る導電部材及びその製造方法について、図面に基づき詳細に説明する。なお、第一実施形態と同一構成には同一符号を付し、重複する説明は省略する。 [Fourth embodiment]
Next, the conductive member and the manufacturing method thereof according to the fourth embodiment of the present invention will be described in detail with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same structure as 1st embodiment, and the overlapping description is abbreviate | omitted.
　上記第一～第三実施形態の導電部材（導電構造体）は、基材として金属基材（金属板）を使用している。しかし、本実施形態に係る導電部材（導電構造体）は、基材として多孔質材料を使用しており、その用途としては、燃料電池用ガス拡散層を挙げることができる。そのため、以後、本実施形態の導電部材の構成について、導電部材をガス拡散層として使用した場合を例に説明する。 The conductive member (conductive structure) of the first to third embodiments uses a metal substrate (metal plate) as a substrate. However, the conductive member (conductive structure) according to the present embodiment uses a porous material as a base material, and the use thereof includes a gas diffusion layer for a fuel cell. Therefore, hereinafter, the configuration of the conductive member of the present embodiment will be described by taking the case where the conductive member is used as a gas diffusion layer as an example.
　当該ガス拡散層は、多孔質材料層と、前記多孔質材料層の表面上又は中に存在する導電性炭素層又は導電性炭素粒子を含む。さらに、前記導電性炭素層又は導電性炭素粒子において、ラマン散乱分光分析より測定されたＤ－バンドピーク強度ＩＤとＧ－バンドピーク強度ＩＧの強度比Ｒ（ＩＤ／ＩＧ）が１．３以上である。加えて、前記導電性炭素層のラマン散乱分光分析による回転異方性測定により測定された平均ピークが、２回対称パターンを示す。 The gas diffusion layer includes a porous material layer and a conductive carbon layer or conductive carbon particles present on or in the surface of the porous material layer. Further, in the conductive carbon layer or conductive carbon particles, the intensity ratio of the measured from the Raman scattering spectroscopy D- band peak intensity I D and G- band peak intensity I G R (I D / I G) is 1 .3 or more. In addition, the average peak measured by rotational anisotropy measurement by Raman scattering spectroscopy of the conductive carbon layer shows a two-fold symmetrical pattern.
　後述するように、前記多孔質材料層は、炭素繊維、金属繊維及び有機繊維よりなる群から選択される一種以上を含むことができる。ここで、炭素繊維としては、黒鉛化されていないが、炭素化まで行われた炭素繊維が存在する。炭素化まで行われた炭素繊維は黒鉛化された炭素繊維と比較して安価であるため、建物の強度補強部材などに使用されている。しかし、炭素化まで行われた炭素繊維は、黒鉛化された炭素繊維に比べて導電性に劣る。一方、金属繊維、例えば貴金属で構成される繊維ならば導電性は十分に高いが、非常に高価であり実用に沿わない。これに対し、安価な金属で構成される金属繊維では、表面の酸化皮膜形成による導電性の低下が生じる。換言すれば、酸化皮膜による導電性の不足が金属繊維を使用する際の技術的課題である。 As described later, the porous material layer may include one or more selected from the group consisting of carbon fiber, metal fiber, and organic fiber. Here, as the carbon fiber, there is a carbon fiber that has not been graphitized but has been carbonized. Since carbon fibers that have been carbonized are less expensive than graphitized carbon fibers, they are used as strength reinforcing members for buildings. However, carbon fibers that have been carbonized are inferior in electrical conductivity compared to graphitized carbon fibers. On the other hand, a metal fiber, for example, a fiber composed of a noble metal, has a sufficiently high conductivity, but is very expensive and not practical. On the other hand, in the metal fiber comprised with an inexpensive metal, the electroconductivity fall by surface oxide film formation arises. In other words, the lack of conductivity due to the oxide film is a technical problem when using metal fibers.
　また、特開２００８－１５３２００号公報のガス拡散層では、黒鉛化処理まで行った導電性の高いカーボンファイバを用いたシート状の基材を使用している。しかし、カーボンファイバを黒鉛化処理するためには、２０００℃以上の高温処理をするため、コストが大幅に上がるという問題がある。 In addition, in the gas diffusion layer disclosed in Japanese Patent Application Laid-Open No. 2008-153200, a sheet-like base material using a carbon fiber having high conductivity that has been subjected to graphitization is used. However, in order to graphitize the carbon fiber, a high temperature treatment of 2000 ° C. or higher is required, so that there is a problem that the cost is significantly increased.
　このような技術的課題に鑑みて、本実施形態の技術的原理は以下の通りである。即ち、前記多孔質材料層を、導電性が十分でない安価な繊維で形成した場合でも、導電性炭素層又は導電性炭素粒子を前記繊維に被覆することによって、燃料電池に適用可能なＧＤＬを得ることである。すなわち、本実施形態に係る燃料電池用ＧＤＬは、高導電性と低コストとを共に実現するＧＤＬである。 In view of such technical problems, the technical principle of the present embodiment is as follows. That is, even when the porous material layer is formed of an inexpensive fiber having insufficient conductivity, a GDL applicable to a fuel cell is obtained by covering the fiber with a conductive carbon layer or conductive carbon particles. That is. That is, the GDL for a fuel cell according to the present embodiment is a GDL that realizes both high conductivity and low cost.
　なお、本実施形態では、多孔質材料層を構成する炭素繊維中の導電性の炭素を、「多孔質材料層を構成する導電性の炭素」と称する。一方、導電性炭素層又は導電性炭素粒子を、単に「導電性の炭素」とも称し、双方の導電性の炭素を区別する。 In the present embodiment, the conductive carbon in the carbon fiber constituting the porous material layer is referred to as “conductive carbon constituting the porous material layer”. On the other hand, the conductive carbon layer or the conductive carbon particles is also simply referred to as “conductive carbon” to distinguish both conductive carbons.
　本実施形態によれば、多孔質材料層上に導電性炭素層又は導電性炭素粒子を配置してなるＧＤＬと、隣接する部材との接触抵抗が有意に低減する。また、導電性炭素層又は導電性炭素粒子の配置によって、多孔質材料層を構成する多孔質材料の細孔径コントロールが可能となり、燃料電池内における気体及び液水の排出性を向上させることができる。なお、前記導電性炭素層は多孔質材料層の表面上に存在するか、多孔質材料層（繊維質）の内部に存在する。一方、導電性炭素粒子は多孔質材料層の内部に存在する場合が殆どである。 According to this embodiment, the contact resistance between the GDL formed by disposing the conductive carbon layer or the conductive carbon particles on the porous material layer and the adjacent member is significantly reduced. In addition, the arrangement of the conductive carbon layer or the conductive carbon particles makes it possible to control the pore diameter of the porous material constituting the porous material layer, thereby improving the gas and liquid water dischargeability in the fuel cell. . The conductive carbon layer is present on the surface of the porous material layer or is present inside the porous material layer (fibrous material). On the other hand, the conductive carbon particles are mostly present inside the porous material layer.
　本実施形態に係る固体高分子形燃料電池（ＰＥＦＣ）も第一実施形態に係るＰＥＦＣと同様の基本構成を有する。具体的には、図１に示すように、水素イオンを選択的に輸送する固体高分子電解質膜２の両面に、アノード触媒層３ａ及びカソード触媒層３ｂがそれぞれ密着して配置されている。さらに、触媒層３（３ａ、３ｂ）の外面にはそれぞれ、ガス透過性と導電性とを兼ね備えた、アノードガス拡散層４ａ及びカソードガス拡散層４ｂが密着して配置されている。また、前記ガス拡散層４（４ａ、４ｂ）及び固体高分子電解質膜２から膜電極接合体９が構成される。 The polymer electrolyte fuel cell (PEFC) according to this embodiment also has the same basic configuration as the PEFC according to the first embodiment. Specifically, as shown in FIG. 1, an anode catalyst layer 3a and a cathode catalyst layer 3b are disposed in close contact with both surfaces of a solid polymer electrolyte membrane 2 that selectively transports hydrogen ions. Further, an anode gas diffusion layer 4a and a cathode gas diffusion layer 4b having both gas permeability and conductivity are arranged in close contact with each other on the outer surface of the catalyst layer 3 (3a, 3b). A membrane electrode assembly 9 is constituted by the gas diffusion layer 4 (4a, 4b) and the solid polymer electrolyte membrane 2.
　前記ガス拡散層の外側には、膜電極接合体９を機械的に接合するとともに、隣接するＭＥＡ同士を、互いに電気的に直列となるように接続する導電性のアノードセパレータ５ａ及びカソードセパレータ５ｂが配置されている。そして、隣り合うセパレータ（５ａ、５ｂ）及びガス拡散層（４ａ、４ｂ）は導電部材（８ａ、８ｂ）を構成する。 Outside the gas diffusion layer, there are a conductive anode separator 5a and a cathode separator 5b that mechanically join the membrane electrode assembly 9 and connect adjacent MEAs so as to be electrically in series with each other. Has been placed. Adjacent separators (5a, 5b) and gas diffusion layers (4a, 4b) constitute conductive members (8a, 8b).
　ここで、ガス拡散層４（４ａ、４ｂ）として、本実施形態に係る燃料電池用ＧＤＬを用いることにより、高導電性と低コストとを共に実現することができる。ひいては、高性能かつ安価なＰＥＦＣ１を得ることができる。 Here, as the gas diffusion layer 4 (4a, 4b), by using the GDL for fuel cell according to the present embodiment, both high conductivity and low cost can be realized. As a result, high-performance and inexpensive PEFC 1 can be obtained.
　図３４は、本実施形態に係るガス拡散層の概略構成を示す断面図である。本実施形態において、ガス拡散層３５１は、導電体として多孔質材料層３５２及び導電性炭素層３５４を有する。そして、これらの層間には、必須ではないが、中間層３５６が介在している。ここで、図３４におけるガス拡散層の断面図は、多孔質材料層の上に中間層及び導電性炭素層が積層された構造を示している。しかし、本実施形態はこの構造に限らず、繊維で構成される多孔質材料層の内部に中間層及び導電性炭素層が「積層」されたような構造などもありうる。ここで、本実施形態における「積層」とは、ある層の上（又は下）に積まれた層を意味する場合に限らず、ある層の内部に構成される層を意味する場合もある。そして、本実施形態ではいずれか一方の「積層」形態のみならず、両方の「積層」形態を共に有する１つのガス拡散層であっても良い。 FIG. 34 is a cross-sectional view showing a schematic configuration of the gas diffusion layer according to the present embodiment. In the present embodiment, the gas diffusion layer 351 includes a porous material layer 352 and a conductive carbon layer 354 as conductors. An intermediate layer 356 is interposed between these layers, although not essential. Here, the cross-sectional view of the gas diffusion layer in FIG. 34 shows a structure in which an intermediate layer and a conductive carbon layer are laminated on the porous material layer. However, the present embodiment is not limited to this structure, and there may be a structure in which an intermediate layer and a conductive carbon layer are “laminated” inside a porous material layer composed of fibers. Here, “lamination” in the present embodiment is not limited to a layer stacked on (or below) a certain layer, but may also mean a layer configured inside a certain layer. In the present embodiment, one gas diffusion layer having both “laminated” forms as well as either “laminated” form may be used.
　また、図３４には親水化層３５８も示されているが、これについては後述する。なお、ＰＥＦＣ１において、セパレータ（５ａ、５ｂ）は、導電性炭素層３５４がＭＥＡ９側に位置するように、配置される。以下、燃料電池用ＧＤＬの各構成要素について詳述する。 FIG. 34 also shows a hydrophilic layer 358, which will be described later. In PEFC1, the separators (5a, 5b) are arranged so that the conductive carbon layer 354 is located on the MEA 9 side. Hereafter, each component of GDL for fuel cells is explained in full detail.
　［多孔質材料層］
　多孔質材料層３５２は、シート状の多孔質材料を基本的な構成とする。そして、多孔質材料層３５２は、炭素繊維、金属繊維及び有機繊維よりなる群から選択される一種以上を含むことが好ましい。この場合、多孔質材料層の製造時の焼成工程において、繊維同士が融着するため、それらの界面における電気抵抗を低減することができる。換言すれば、このような場合、繊維同士の融着によって導電性が有意に高くなるという利点がある。 [Porous material layer]
The porous material layer 352 is basically composed of a sheet-like porous material. And it is preferable that the porous material layer 352 contains 1 or more types selected from the group which consists of carbon fiber, a metal fiber, and an organic fiber. In this case, since the fibers are fused to each other in the firing step during the production of the porous material layer, the electrical resistance at the interface between them can be reduced. In other words, in such a case, there is an advantage that the conductivity is significantly increased by the fusion of the fibers.
　図３５は、多孔質材料層の表面を微視的に表した概略図である。後述するように、上記導電性炭素層３５４は、スパッタリング法により形成することができる。スパッタによる導電性炭素層の成膜は、ターゲット（導電性の炭素）がスパッタリングによって多孔質材料層に対し直線状に向かってくる。そのため、導電性炭素層又は導電性炭素粒子は、スパッタ方向に対して露出した繊維表面にのみ堆積される。したがって、繊維基材自体の角度を変えること、言い換えれば細孔径を適宜調節することにより、当該表面のうち、より広い面上に導電性炭素層又は導電性炭素粒子を配置することができる。 FIG. 35 is a schematic view microscopically showing the surface of the porous material layer. As will be described later, the conductive carbon layer 354 can be formed by a sputtering method. When the conductive carbon layer is formed by sputtering, the target (conductive carbon) is linearly directed to the porous material layer by sputtering. Therefore, the conductive carbon layer or the conductive carbon particles is deposited only on the fiber surface exposed to the sputtering direction. Therefore, by changing the angle of the fiber substrate itself, in other words, by appropriately adjusting the pore diameter, the conductive carbon layer or the conductive carbon particles can be disposed on a wider surface among the surfaces.
　図３５に示されるように、炭素繊維などで構成される多孔質材料層３５２は、多数の繊維（カーボンファイバ（ＣＦ）３５３）が重なったような状態にある。多孔質材料層３５２に対して導電性炭素層３５４をスパッタにより成膜すると、図３５の矢印に示すように、多孔質材料層３５２の主表面へターゲットがスパッタされることとなる。すなわち、導電性炭素層は、多孔質材料層の最表面のみならず、その近傍（多孔質材料層の表面に露出している部分）にも形成される。換言すれば、導電性炭素層は、図３４に示すような多孔質材料層の表面上に積層される形態のみならず、多孔質材料層の中のみに存在する形態及び多孔質材料層の表面上並びに多孔質材料層の中の双方に存在する形態も採り得る。 As shown in FIG. 35, the porous material layer 352 made of carbon fiber or the like is in a state where a large number of fibers (carbon fibers (CF) 353) are overlapped. When the conductive carbon layer 354 is deposited on the porous material layer 352 by sputtering, the target is sputtered onto the main surface of the porous material layer 352 as shown by the arrows in FIG. That is, the conductive carbon layer is formed not only on the outermost surface of the porous material layer but also in the vicinity thereof (portion exposed on the surface of the porous material layer). In other words, the conductive carbon layer has not only the form laminated on the surface of the porous material layer as shown in FIG. 34, but also the form existing only in the porous material layer and the surface of the porous material layer. Forms present both on the top as well as in the porous material layer may also be employed.
　また、多孔質材料層を構成する繊維同士の配置関係として、繊維径を調節することにより、導電性の向上と圧損上昇の防止の両方を実現できる。具体的には、繊維径が大きいほど、繊維中の空隙が大きくなる反面、繊維１本１本の接点の数が減少する。そのため、導電性は低下するが圧損の上昇は防止できる。反対に、繊維径が小さいほど、繊維中の空隙が小さくなる反面、繊維１本１本の接点の数が増大する。そのため、導電性は上昇するが圧損の上昇が大きくなる。したがって、繊維径を適度な範囲に調節することが好ましい。 Further, by adjusting the fiber diameter as the positional relationship between the fibers constituting the porous material layer, it is possible to realize both improvement in conductivity and prevention of an increase in pressure loss. Specifically, the larger the fiber diameter, the larger the voids in the fiber, but the number of contacts per fiber decreases. For this reason, the conductivity is lowered, but an increase in pressure loss can be prevented. On the other hand, the smaller the fiber diameter, the smaller the voids in the fiber, but the number of contacts per fiber increases. Therefore, the conductivity increases, but the pressure loss increases. Therefore, it is preferable to adjust the fiber diameter to an appropriate range.
　なお、本実施形態における「炭素繊維」とは、原料である繊維を不活性雰囲気中１０００℃以上の温度で焼成して得られる繊維を意味する。かかる炭素繊維としては、以下に限定されることはないが、例えば、ポリアクリロニトリル（ＰＡＮ）系炭素繊維、ピッチ系炭素繊維、フェノール系炭素繊維、及び気相成長による炭素繊維などが挙げられる。ＰＡＮ系炭素繊維とは、ＰＡＮが主成分の合成繊維を原料とする繊維である。一方、ピッチ系炭素繊維とは、石油・石炭・合成ピッチ等を原料とする繊維である。 In addition, the “carbon fiber” in the present embodiment means a fiber obtained by firing a raw material fiber in an inert atmosphere at a temperature of 1000 ° C. or higher. Examples of such carbon fibers include, but are not limited to, polyacrylonitrile (PAN) based carbon fibers, pitch based carbon fibers, phenol based carbon fibers, and vapor grown carbon fibers. The PAN-based carbon fiber is a fiber made of synthetic fiber whose main component is PAN. On the other hand, the pitch-based carbon fiber is a fiber made from petroleum, coal, synthetic pitch or the like.
　炭素繊維の平均繊維径は、原料となるＰＡＮやピッチの仕様や製造方法によって好ましい範囲が異なる。なお、従来より市販されているもののうち、平均繊維径の範囲として、ＰＡＮ系では５μｍ～１０μｍ、ピッチ系では５μｍ～２０μｍ、気相成長では数μｍである各炭素繊維を用いることができる。一方、本実施形態に係るＧＤＬに使用可能な炭素繊維の平均繊維長は、特に制限されないが、一般に使用される１０ｍｍ以下（より好ましくは３～６ｍｍ）のチョップドファイバを抄紙して用いることができる。 The preferable range of the average fiber diameter of the carbon fiber varies depending on the specifications of the PAN and pitch as a raw material and the manufacturing method. Among the commercially available products, carbon fibers having an average fiber diameter range of 5 μm to 10 μm for the PAN system, 5 μm to 20 μm for the pitch system, and several μm for the vapor phase growth can be used. On the other hand, the average fiber length of the carbon fiber that can be used for the GDL according to the present embodiment is not particularly limited, but a generally used chopped fiber of 10 mm or less (more preferably 3 to 6 mm) can be made by paper. .
　炭素繊維は電気抵抗率が低いため、多孔質材料層に含まれると、触媒層で発生する電荷をより効率的に集電できる。また、炭素繊維はその優れた比強度・比弾性率から、宇宙航空などの幅広い分野において、各種複合材の強化材として従来より工業的に利用されている。なかでも本実施形態のＧＤＬでは、工業上広く利用されているＰＡＮ系炭素繊維又はピッチ系炭素繊維が好ましい。 Since carbon fiber has a low electric resistivity, when it is contained in the porous material layer, the electric charge generated in the catalyst layer can be collected more efficiently. Carbon fiber has been industrially used as a reinforcing material for various composite materials in a wide range of fields such as aerospace due to its excellent specific strength and specific elastic modulus. Among these, in the GDL of the present embodiment, PAN-based carbon fibers or pitch-based carbon fibers that are widely used in industry are preferable.
　さらに、汎用性、コストパフォーマンスや高導電性という観点より、多孔質材料層は、ＰＡＮ系もしくはピッチ系炭素繊維であって、黒鉛化（脱炭素化）された繊維を含まないことが特に好ましい。ここで、「黒鉛化（脱炭素化）された繊維を含まない」とは、繊維を形成する炭素原子鎖の途中に炭素以外の元素（Ｎ、Ｏ等）が含まれることを意味する。以下、かかる繊維が特に好ましい理由を説明する。 Furthermore, from the viewpoint of versatility, cost performance, and high conductivity, the porous material layer is particularly preferably a PAN-based or pitch-based carbon fiber that does not contain graphitized (decarbonized) fiber. Here, “not containing graphitized (decarbonized) fibers” means that elements other than carbon (N, O, etc.) are included in the middle of the carbon atom chain forming the fibers. Hereinafter, the reason why such a fiber is particularly preferable will be described.
　ＰＡＮ系炭素繊維は強度や伸度に優れる反面、難黒鉛化性であるため、導電性が低いという問題がある。導電性向上を図るため、一般に約２２００～３０００℃という高温での焼成が必要不可欠となるが、同時に強度が低下してしまうという問題がある。また高温焼成による炉の低寿命化など、高コスト化を避けることは極めて困難であり、工業的規模では不利になる。 PAN-based carbon fiber is excellent in strength and elongation, but has a problem of low conductivity because it is non-graphitizable. Generally, firing at a high temperature of about 2200 to 3000 ° C. is indispensable in order to improve conductivity, but there is a problem that the strength decreases at the same time. Moreover, it is extremely difficult to avoid high costs such as shortening the life of the furnace by high-temperature firing, which is disadvantageous on an industrial scale.
　一方、ピッチ系炭素繊維については、等方性ピッチ由来のものと異方性ピッチ由来のものとに大別できるが、高性能を発現する上で、一般に異方性ピッチが用いられる。異方性ピッチ由来の炭素繊維は、その原料（異方性ピッチ）の易黒鉛化の性質から弾性や強度に優れる反面、伸度が低くなるという問題がある。そのため、工業的には炭素繊維の生産性や複合化の際のハンドリング性に劣る可能性がある。 On the other hand, pitch-based carbon fibers can be broadly classified into those derived from isotropic pitches and those derived from anisotropic pitches, but anisotropic pitches are generally used in order to achieve high performance. The carbon fiber derived from anisotropic pitch is excellent in elasticity and strength due to the graphitizable nature of the raw material (anisotropic pitch), but has a problem of low elongation. Therefore, industrially, there is a possibility that the productivity of carbon fiber and the handling property at the time of compounding are inferior.
　これらのＰＡＮ系炭素繊維やピッチ系炭素繊維の問題に鑑みて、ＰＡＮ系炭素繊維とピッチ系炭素繊維の両者の欠点を補うために、両者の複合化の検討が種々なされている。しかし、工程の複雑化に起因するコストアップや品質の低下等、多くの問題があり、工業上利用することは困難であるというのが現実である。 In view of the problems of these PAN-based carbon fibers and pitch-based carbon fibers, in order to compensate for the disadvantages of both PAN-based carbon fibers and pitch-based carbon fibers, various studies have been made on combining them. However, there are many problems such as an increase in cost and a decrease in quality due to the complexity of the process, and the reality is that it is difficult to use industrially.
　これに対し、本実施形態では、ＰＡＮ系もしくはピッチ系炭素繊維であって、黒鉛化された繊維を含まない繊維で多孔質材料層を構成することにより、上記のような問題は生じない。そして、黒鉛化繊維を含まない炭素繊維からなる多孔質材料層の導電性の低下については、後述する導電性炭素層の存在によってカバーすることができる。このようにして、本実施形態に係る燃料電池用ガス拡散層は、高導電性と低コストとを共に実現することができる。なお、本明細書における「黒鉛化繊維」とは、炭素繊維の導電性を向上させる目的で、不活性ガス雰囲気中２０００℃以上の温度で焼成して得られる繊維を意味する。 On the other hand, in the present embodiment, the above-described problem does not occur by configuring the porous material layer with fibers that are PAN-based or pitch-based carbon fibers and do not include graphitized fibers. And about the electroconductive fall of the porous material layer which consists of carbon fiber which does not contain a graphitized fiber, it can cover by presence of the electroconductive carbon layer mentioned later. In this way, the fuel cell gas diffusion layer according to the present embodiment can achieve both high conductivity and low cost. The “graphitized fiber” in the present specification means a fiber obtained by firing at a temperature of 2000 ° C. or higher in an inert gas atmosphere for the purpose of improving the conductivity of the carbon fiber.
　図３６は、ＰＡＮ系炭素繊維の製造の各工程における繊維の変化を示す概略図である。従来より、ＰＡＮ系炭素繊維に高い導電性を付与するために、最終的に黒鉛化処理を施すことにより結晶化させている。このような、ＰＡＮ系炭素繊維の製造に際して、従来より行われている黒鉛化処理は、多孔質材料層の大幅な導電性向上を実現する反面、多孔質材料自体が大幅にコストアップしてしまう。すなわち、ＰＡＮ系炭素繊維の製造の中でも、黒鉛化処理に大部分のコストが費やされる。これに対し、本実施形態に係るガス拡散層がＰＡＮ系炭素繊維を含む場合、ＰＡＮ系炭素繊維の製造において黒鉛化処理を行わない。したがって、図３６に示すように、変化した繊維は黒鉛化繊維ではなく炭素化繊維と言い得る。しかし、前記炭素化繊維には、「炭素－炭素」結合の途中に窒素原子が存在するため、ＰＡＮ系炭素繊維としての導電性は、黒鉛化繊維よりも炭素化繊維の方がはるかに劣る。 FIG. 36 is a schematic view showing a change in fiber in each step of manufacturing the PAN-based carbon fiber. Conventionally, in order to impart high conductivity to the PAN-based carbon fiber, it is finally crystallized by performing a graphitization treatment. In the production of such a PAN-based carbon fiber, the graphitization treatment that has been conventionally performed realizes a significant improvement in the conductivity of the porous material layer, while the cost of the porous material itself greatly increases. . That is, most of the cost is spent on the graphitization treatment in the production of the PAN-based carbon fiber. On the other hand, when the gas diffusion layer according to the present embodiment includes PAN-based carbon fibers, no graphitization treatment is performed in the manufacture of the PAN-based carbon fibers. Therefore, as shown in FIG. 36, the changed fiber can be referred to as carbonized fiber instead of graphitized fiber. However, since the carbonized fiber has nitrogen atoms in the middle of the “carbon-carbon” bond, the conductivity of the PAN-based carbon fiber is much lower than that of the graphitized fiber.
　そこで、本実施形態によれば、前記多孔質材料層の表面上又は内部に、導電性炭素層又は導電性炭素粒子を含むことによって、黒鉛化処理を実施しなくても、結果的に高い導電性を得ることができる。これにより、高い導電性と大幅なコストダウンとを共に実現できる。さらに、従来より行われている黒鉛化処理によって、多孔質材料層中の気孔率が上がりすぎる場合がある。これに対し、本実施形態によれば、導電性炭素層又は導電性炭素粒子を含有させることにより、黒鉛化処理の省略が可能となり、余計な高気孔率化を防止できる。 Therefore, according to the present embodiment, by including a conductive carbon layer or conductive carbon particles on or in the surface of the porous material layer, the result is high conductivity without performing graphitization. Sex can be obtained. Thereby, both high conductivity and a significant cost reduction can be realized. Furthermore, the porosity in the porous material layer may be excessively increased by the graphitization treatment that has been conventionally performed. On the other hand, according to this embodiment, by including a conductive carbon layer or conductive carbon particles, it is possible to omit the graphitization treatment, and it is possible to prevent an excessive increase in porosity.
　有機繊維とは、導電化した樹脂繊維を意味する。前記導電化した樹脂繊維とは、炭素原子を多く含み、焼成によって容易に炭素化されて炭素繊維を形成し、その結果、導電性が発現する繊維のことである。有機繊維としては、以下に制限されることはないが、例えば、フェノール系樹脂繊維、ポリアクリロニトリル繊維、ポリエチレンテレフタレート繊維やポリブチレンテレフタレート繊維などが挙げられる。なかでも、一層確実に導電性を確保できるという観点より、多孔質材料層はフェノール系樹脂繊維を含むことが好ましい。 Organic fiber means conductive resin fiber. The conductive resin fiber is a fiber that contains many carbon atoms and is easily carbonized by firing to form a carbon fiber, and as a result, exhibits conductivity. Examples of the organic fiber include, but are not limited to, phenolic resin fiber, polyacrylonitrile fiber, polyethylene terephthalate fiber, and polybutylene terephthalate fiber. Especially, it is preferable that a porous material layer contains a phenol-type resin fiber from a viewpoint that electrical conductivity can be ensured more reliably.
　有機繊維の繊維径の範囲として、好ましくは５μｍ～５０μｍ、より好ましくは１０μｍ～３０μｍである。一方、有機繊維の繊維長は、有機繊維の状態ではチョップドされないことから、特に制限されない。 The fiber diameter range of the organic fiber is preferably 5 μm to 50 μm, more preferably 10 μm to 30 μm. On the other hand, the fiber length of the organic fiber is not particularly limited because it is not chopped in the state of the organic fiber.
　金属繊維としては、鉄、チタン、アルミニウム及び銅並びにこれらの合金；ステンレス；金や銀などの貴金属の繊維が挙げられる。なかでも、機械的強度、汎用性、コスト面、加工容易性や高導電性の観点からいえば、多孔質材料層３５２はステンレス、アルミニウム又はアルミニウム合金の繊維を含むことが好ましい。特に、機械的強度、汎用性、コスト面、加工容易性や高導電性のみならず、燃料電池セル内の酸性雰囲気に十分な耐性を有するため、多孔質材料層３５２はステンレスの繊維を含むことが一層好ましい。なお、多孔質材料層がステンレス繊維を含む場合、セパレータを構成する多孔質材料層との接触面の導電性が十分に確保される。その結果、たとえリブ肩部の膜の隙間などに水分が浸入したとしても、ステンレスから構成される多孔質材料層自体に生じる酸化皮膜の耐食性によって、セパレータの耐久性が維持される。 Examples of metal fibers include iron, titanium, aluminum, copper, and alloys thereof; stainless steel; fibers of precious metals such as gold and silver. In particular, from the viewpoint of mechanical strength, versatility, cost, ease of processing, and high conductivity, the porous material layer 352 preferably includes stainless steel, aluminum, or aluminum alloy fibers. In particular, the porous material layer 352 contains stainless steel fibers in order to have not only mechanical strength, versatility, cost, ease of processing and high conductivity, but also sufficient resistance to an acidic atmosphere in the fuel cell. Is more preferable. In addition, when a porous material layer contains a stainless fiber, the electroconductivity of a contact surface with the porous material layer which comprises a separator is fully ensured. As a result, the durability of the separator is maintained by the corrosion resistance of the oxide film formed on the porous material layer itself made of stainless steel even if moisture enters the gaps in the rib shoulder film.
　金属繊維の繊維径の範囲として、好ましくは１μｍ～１００μｍ、より好ましくは５μｍ～５０μｍ、さらに好ましくは５μｍ～２０μｍである。一方、本実施形態に係るＧＤＬに使用可能な金属繊維の繊維長は、一般に使用される１０ｍｍ以下のチョップドファイバを抄紙して用いることができる。なお、チョップドファイバは、５ｍｍ～１０ｍｍであることがより好ましい。 The fiber diameter range of the metal fiber is preferably 1 μm to 100 μm, more preferably 5 μm to 50 μm, and still more preferably 5 μm to 20 μm. On the other hand, the fiber length of the metal fiber that can be used for the GDL according to the present embodiment can be made by making a paper of a chopped fiber of 10 mm or less that is generally used. The chopped fiber is more preferably 5 mm to 10 mm.
　ステンレスとしては、第一実施形態で詳述したオーステナイト系、マルテンサイト系、フェライト系、オーステナイト・フェライト系、析出硬化系などが挙げられる。また、アルミニウム合金としては、第一実施形態で詳述した純アルミニウム系、及びアルミニウム・マンガン系、アルミニウム・マグネシウム系などが挙げられる。 Examples of stainless steel include austenite, martensite, ferrite, austenite / ferrite, precipitation hardening, and the like detailed in the first embodiment. Examples of the aluminum alloy include the pure aluminum series, the aluminum / manganese series, and the aluminum / magnesium series described in detail in the first embodiment.
　一方、多孔質材料層３５２には機械的な強度や成形性も求められるため、上記の合金種に加えて、合金の調質も適宜選択される。なお、多孔質材料層３５２がチタンやアルミニウムの単体から構成される場合、当該チタンやアルミニウムの純度は、好ましくは９５質量％以上であり、より好ましくは９７質量％以上であり、さらに好ましくは９９質量％以上である。 On the other hand, since the mechanical strength and formability are also required for the porous material layer 352, the tempering of the alloy is appropriately selected in addition to the above alloy types. Note that when the porous material layer 352 is composed of titanium or aluminum alone, the purity of the titanium or aluminum is preferably 95% by mass or more, more preferably 97% by mass or more, and still more preferably 99%. It is at least mass%.
　ここで、前記多孔質材料層は、炭素繊維、金属繊維及び有機繊維よりなる群から選択される二種以上を含んでも良い。前記多孔質材料層を構成する繊維が、炭素繊維及び金属繊維からなる場合を例に説明する。これら炭素繊維及び金属繊維の関係は、炭素繊維と金属繊維を単に混合した形態でも良いし、１本の炭素繊維を被覆するように、外周縁に金属繊維が存在する形態であっても良い。 Here, the porous material layer may include two or more selected from the group consisting of carbon fibers, metal fibers, and organic fibers. The case where the fiber which comprises the said porous material layer consists of a carbon fiber and a metal fiber is demonstrated to an example. The relationship between the carbon fiber and the metal fiber may be a form in which the carbon fiber and the metal fiber are simply mixed, or may be a form in which the metal fiber is present on the outer periphery so as to cover one carbon fiber.
　また、前記多孔質材料層は、導電性を有さない繊維やその他の成分を含んでも良い。しかし、本実施形態に係るガス拡散層が十分な導電性を有するという観点から、多孔質材料層の構成成分を１００質量％とした場合に、前記導電性を有さない成分の含有量は５０質量％以下であることが好ましい。また、１０質量％以下であることがより好ましく、多孔質材料層が導電性を有さない成分を実質的に含まないことが特に好ましい。 In addition, the porous material layer may include non-conductive fibers and other components. However, from the viewpoint that the gas diffusion layer according to this embodiment has sufficient conductivity, when the constituent component of the porous material layer is 100% by mass, the content of the component having no conductivity is 50. It is preferable that it is below mass%. Moreover, it is more preferable that it is 10 mass% or less, and it is especially preferable that a porous material layer does not contain the component which does not have electroconductivity substantially.
　［導電性炭素層］
　導電性炭素層３５４は、導電性炭素を含む層である。そして、上述のように、多孔質材料層において低コストを図る代償としての導電性の低下を、導電性炭素層の存在によってカバーすることができる。これは、特に炭素繊維（なかでもＰＡＮ系もしくはピッチ系炭素繊維）の場合が該当する。また、多孔質材料層として金属繊維を用いた場合には、導電性炭素層の存在により、ガス拡散層としての導電性を確保しつつ、多孔質材料層３５２のみの場合と比較して耐食性が改善される。 [Conductive carbon layer]
The conductive carbon layer 354 is a layer containing conductive carbon. And as above-mentioned, the electroconductive fall as a price which aims at low cost in a porous material layer can be covered by presence of an electroconductive carbon layer. This is particularly the case for carbon fibers (in particular, PAN-based or pitch-based carbon fibers). Further, when metal fibers are used as the porous material layer, the presence of the conductive carbon layer ensures corrosion resistance as compared with the case of only the porous material layer 352 while ensuring the conductivity as the gas diffusion layer. Improved.
　本実施形態における導電性炭素層又は導電性炭素粒子において、ラマン散乱分光分析より測定されたＤ－バンドピーク強度ＩＤとＧ－バンドピーク強度ＩＧの強度比Ｒ（ＩＤ／ＩＧ）が１．３以上である。加えて、前記導電性炭素層のラマン散乱分光分析による回転異方性測定により測定された平均ピークが、２回対称パターンを示す。 In the conductive carbon layer or conductive carbon particles in the present embodiment, the intensity ratio of the measured from the Raman scattering spectroscopy D- band peak intensity I D and G- band peak intensity I G R (I D / I G) is 1.3 or more. In addition, the average peak measured by rotational anisotropy measurement by Raman scattering spectroscopy of the conductive carbon layer shows a two-fold symmetrical pattern.
　後述するが、強度比Ｒ（ＩＤ／ＩＧ）が１．３以上である前記導電性炭素層又は導電性炭素粒子の大部分は、多孔質材料層の表面上又は中に設けられ、多結晶グラファイトとして存在する。そして、前記「多結晶グラファイト」とは、グラフェン面（六角網面）が積層した異方性のグラファイト結晶構造（グラファイトクラスタ）を有する。したがって、前記導電性炭素層又は導電性炭素粒子の大部分は、その強度比Ｒ（ＩＤ／ＩＧ）が１．３以上であるが故に、グラフェン面を有する積層体を構成する。 As will be described later, most of the conductive carbon layer or the conductive carbon particles having an intensity ratio R (I D / I G ) of 1.3 or more is provided on or in the surface of the porous material layer. Present as crystalline graphite. The “polycrystalline graphite” has an anisotropic graphite crystal structure (graphite cluster) in which graphene surfaces (hexagonal network surfaces) are laminated. Therefore, most of the conductive carbon layer or the conductive carbon particles constitute a laminate having a graphene surface because the strength ratio R (I D / I G ) is 1.3 or more.
　そして、第一実施形態でも詳述したように、Ｄバンドピーク強度（ＩＤ）とＧバンドピーク強度（ＩＧ）との強度比Ｒ（ＩＤ／ＩＧ）は、炭素材料のグラファイトクラスタサイズやグラファイト構造の乱れ具合（結晶構造欠陥性）、ｓｐ２結合比率などの指標として用いられる。すなわち、本実施形態においては、導電性炭素層３５４の接触抵抗の指標とすることができ、導電性炭素層３５４の導電性を制御する膜質パラメータとして用いることができる。なお、Ｒ（ＩＤ／ＩＧ）値は、第一実施形態と同様に、炭素材料のラマンスペクトルを計測することにより算出される。 As described in detail in the first embodiment, the intensity ratio R (I D / I G ) between the D band peak intensity (I D ) and the G band peak intensity (I G ) is the graphite cluster size of the carbon material. It is used as an indicator such as the degree of disorder of the graphite structure (crystal structure defect) and the sp 2 bond ratio. That is, in this embodiment, it can be used as an index of contact resistance of the conductive carbon layer 354, and can be used as a film quality parameter for controlling the conductivity of the conductive carbon layer 354. Note that the R (I D / I G ) value is calculated by measuring the Raman spectrum of the carbon material, as in the first embodiment.
　上述したように、本実施形態において、Ｒ値は１．３以上である。また、Ｒ値は、好ましくは１．４～２．０であり、より好ましくは１．４～１．９であり、さらに好ましくは１．５～１．８である。Ｒ値が１．３以上であれば、積層方向の導電性が十分に確保された導電性炭素層を得ることができる。また、Ｒ値が２．０以下であれば、グラファイト成分の減少、すなわちグラファイト構造の乱れ度合を効果的に抑制できる。さらに、導電性炭素層自体の内部応力の増大をも抑制でき、下地である多孔質材料層又は中間層との密着性を一層向上させることができる。 As described above, in this embodiment, the R value is 1.3 or more. The R value is preferably 1.4 to 2.0, more preferably 1.4 to 1.9, and further preferably 1.5 to 1.8. When the R value is 1.3 or more, a conductive carbon layer in which the conductivity in the stacking direction is sufficiently secured can be obtained. Moreover, if R value is 2.0 or less, the reduction | decrease of a graphite component, ie, the disorder degree of a graphite structure, can be suppressed effectively. Furthermore, an increase in internal stress of the conductive carbon layer itself can be suppressed, and adhesion with the porous material layer or the intermediate layer which is the base can be further improved.
　なお、本実施形態のようにＲ値を１．３以上とすることによって上述の作用効果が得られるメカニズムは、第一実施形態で説明したように推定される。つまり、Ｒ値を上述の値に制御することで、グラファイトクラスタ量やサイズが適度に確保され、導電性炭素層３５４の一方の面から他方の面への導電パスが確保される。その結果、多孔質材料層３５２に加えて導電性炭素層３５４を別途設けたことにより、導電性の低下が防止されると考えられる。 In addition, the mechanism by which the above-mentioned effect is acquired by making R value 1.3 or more like this embodiment is estimated as demonstrated in 1st embodiment. That is, by controlling the R value to the above value, the amount and size of the graphite clusters are appropriately secured, and a conductive path from one surface of the conductive carbon layer 354 to the other surface is ensured. As a result, it is considered that the conductive carbon layer 354 is separately provided in addition to the porous material layer 352, so that a decrease in conductivity is prevented.
　ここで、本実施形態の導電性炭素層３５４が多結晶グラファイトから構成される場合、多結晶グラファイトを構成するグラファイトクラスタのサイズは特に制限されない。一例を挙げると、グラファイトクラスタの平均直径は、好ましくは１ｎｍ～５０ｎｍ程度であり、より好ましくは２ｎｍ～１０ｎｍである。グラファイトクラスタの平均直径がこのような範囲内の値であると、多結晶グラファイトの結晶構造を維持しつつ、導電性炭素層３５４の厚膜化を防止することが可能である。なお、グラファイトクラスタの「直径」は、第一実施形態と同様に測定することができる。 Here, when the conductive carbon layer 354 of the present embodiment is made of polycrystalline graphite, the size of the graphite cluster constituting the polycrystalline graphite is not particularly limited. As an example, the average diameter of the graphite cluster is preferably about 1 nm to 50 nm, more preferably 2 nm to 10 nm. When the average diameter of the graphite cluster is within such a range, it is possible to prevent the conductive carbon layer 354 from being thickened while maintaining the crystal structure of the polycrystalline graphite. The “diameter” of the graphite cluster can be measured in the same manner as in the first embodiment.
　なお、本実施形態では導電性炭素層３５４は多結晶グラファイトのみから構成されても良いが、導電性炭素層３５４は多結晶グラファイト以外の材料をも含むことができる。多結晶グラファイト以外の炭素材料としては、カーボンブラック等のグラファイト粒子、並びにフラーレン、カーボンナノチューブ、カーボンナノファイバ、カーボンナノホーン及びカーボンフィブリル等が挙げられる。また、カーボンブラックの具体例として、以下に制限されることはないが、ケッチェンブラック、アセチレンブラック、チャンネルブラック、ランプブラック、オイルファーネスブラックやサーマルブラック等が挙げられる。なお、カーボンブラックは、グラファイト化処理が施されていても良い。また、導電性炭素層３５４に含まれる炭素以外の材料として、金（Ａｕ）、銀（Ａｇ）、白金（Ｐｔ）、ルテニウム（Ｒｕ）、パラジウム（Ｐｄ）、ロジウム（Ｒｈ）、インジウム（Ｉｎ）等の貴金属が挙げられる。また、ポリテトラフルオロエチレン（ＰＴＦＥ）等の撥水性物質、及び導電性酸化物なども挙げられる。多結晶グラファイト以外の材料は、一種のみが用いられても良いし、二種以上が併用されても良い。 In the present embodiment, the conductive carbon layer 354 may be composed only of polycrystalline graphite, but the conductive carbon layer 354 can also include materials other than polycrystalline graphite. Examples of carbon materials other than polycrystalline graphite include graphite particles such as carbon black, and fullerenes, carbon nanotubes, carbon nanofibers, carbon nanohorns, and carbon fibrils. Specific examples of carbon black include, but are not limited to, ketjen black, acetylene black, channel black, lamp black, oil furnace black, and thermal black. Carbon black may be subjected to a graphitization treatment. In addition, as a material other than carbon contained in the conductive carbon layer 354, gold (Au), silver (Ag), platinum (Pt), ruthenium (Ru), palladium (Pd), rhodium (Rh), indium (In) And noble metals. Moreover, water-repellent substances such as polytetrafluoroethylene (PTFE), conductive oxides, and the like can also be given. As for materials other than polycrystalline graphite, only 1 type may be used and 2 or more types may be used together.
　導電性炭素層３５４の厚さは、特に制限されない。ただし、好ましくは１ｎｍ～１０００ｎｍであり、より好ましくは２ｎｍ～５００ｎｍであり、さらに好ましくは５ｎｍ～２００ｎｍである。導電性炭素層の厚さがこのような範囲内の値であれば、ガス拡散層を構成する多孔質材料層とセパレータとの間に十分な導電性を確保することができる。また、多孔質材料層に対して高い耐食機能を持たせることができる。 The thickness of the conductive carbon layer 354 is not particularly limited. However, it is preferably 1 nm to 1000 nm, more preferably 2 nm to 500 nm, and further preferably 5 nm to 200 nm. If the thickness of the conductive carbon layer is within such a range, sufficient conductivity can be ensured between the porous material layer constituting the gas diffusion layer and the separator. Moreover, a high corrosion resistance function can be given to the porous material layer.
　さらに、第一実施形態における導電性炭素層３３と同様の観点から、導電性炭素層３５４のラマン散乱分光分析について、ラマン散乱分光分析の回転異方性測定により測定された平均ピークが、２回対称パターンを示すことが好ましい。回転異方性測定により測定された平均ピークが２回対称パターンを示すということは、導電性炭素層３５４を構成するグラフェン面の面方向が、導電性炭素層３５４の積層方向とほぼ一致していることを意味する。そのため、導電性炭素層３５４における導電性が最短のパスによって確保されることとなる。 Further, from the same viewpoint as that of the conductive carbon layer 33 in the first embodiment, the average peak measured by the rotational anisotropy measurement of the Raman scattering spectroscopic analysis for the Raman scattering spectroscopic analysis of the conductive carbon layer 354 is twice. Preferably it exhibits a symmetrical pattern. The average peak measured by the rotational anisotropy measurement shows a two-fold symmetry pattern. This means that the surface direction of the graphene surface constituting the conductive carbon layer 354 is substantially coincident with the stacking direction of the conductive carbon layer 354. Means that Therefore, the conductivity in the conductive carbon layer 354 is ensured by the shortest path.
　また、第一実施形態における導電性炭素層３３と同様の観点から、導電性炭素層３５４のビッカース硬度は、好ましくは１５００Ｈｖ以下であり、より好ましくは１２００Ｈｖ以下であり、さらに好ましくは１０００Ｈｖ以下であり、特に好ましくは８００Ｈｖ以下である。ビッカース硬度がこのような範囲内の値であれば、導電性を有しないｓｐ３炭素の過剰な混入が抑制され、導電性炭素層３５４の導電性の低下が防止される。一方、ビッカース硬度の下限値について特に制限はないが、ビッカース硬度が５０Ｈｖ以上であれば、導電性炭素層３５４の硬度が十分に確保される。その結果、外部からの接触や摩擦等の衝撃にも耐えることができ、多孔質材料層３５２との密着性にも優れた導電性炭素層３５４が提供される。このような観点から、導電性炭素層３５４のビッカース硬度は、より好ましくは８０Ｈｖ以上であり、さらに好ましくは１００Ｈｖ以上であり、特に好ましくは２００Ｈｖ以上である。 In addition, from the same viewpoint as the conductive carbon layer 33 in the first embodiment, the Vickers hardness of the conductive carbon layer 354 is preferably 1500 Hv or less, more preferably 1200 Hv or less, and further preferably 1000 Hv or less. Especially preferably, it is 800 Hv or less. When the Vickers hardness is a value within such a range, excessive mixing of sp 3 carbon having no conductivity is suppressed, and a decrease in conductivity of the conductive carbon layer 354 is prevented. On the other hand, the lower limit value of the Vickers hardness is not particularly limited, but if the Vickers hardness is 50 Hv or higher, the hardness of the conductive carbon layer 354 is sufficiently ensured. As a result, a conductive carbon layer 354 that can withstand impacts such as external contact and friction and has excellent adhesion to the porous material layer 352 is provided. From such a viewpoint, the Vickers hardness of the conductive carbon layer 354 is more preferably 80 Hv or more, further preferably 100 Hv or more, and particularly preferably 200 Hv or more.
　さらに第一実施形態における導電性炭素層３３と同様の観点から、導電性炭素層３５４における水素原子の含有量は、導電性炭素層３５４を構成する全原子に対して、好ましくは３０原子％以下であり、より好ましくは２０原子％以下であり、さらに好ましくは１０原子％以下である。 Further, from the same viewpoint as that of the conductive carbon layer 33 in the first embodiment, the content of hydrogen atoms in the conductive carbon layer 354 is preferably 30 atomic% or less with respect to all atoms constituting the conductive carbon layer 354. More preferably, it is 20 atomic% or less, More preferably, it is 10 atomic% or less.
　本実施形態においては、多孔質材料層３５２の面全体が、直接的に、又は中間層３５６を介して間接的に、導電性炭素層３５４によって被覆されることが好ましい。換言すれば、導電性炭素層３５４により多孔質材料層３５２が被覆された面積の割合（被覆率）は１００％であることが好ましい。ただし、このような形態に限定されず、被覆率は１００％未満であっても良い。 In the present embodiment, the entire surface of the porous material layer 352 is preferably covered with the conductive carbon layer 354 directly or indirectly via the intermediate layer 356. In other words, the ratio (coverage) of the area where the porous material layer 352 is covered with the conductive carbon layer 354 is preferably 100%. However, it is not limited to such a form, and the coverage may be less than 100%.
　多孔質材料層３５２が金属繊維を含む場合（特に多孔質材料層３５２が金属繊維からなる場合）、上記被覆率は、好ましくは５０％以上である。つまり、金属繊維を含む多孔質材料層３５２の表面の５０％以上を「導電性の炭素」で被覆することが好ましい。また、より好ましくは８０％以上であり、さらに好ましくは９０％以上であり、最も好ましくは１００％である。このような構成とすることにより、導電性炭素層３５４により被覆されていない、多孔質材料層３５２の露出部への酸化皮膜の形成に伴う導電性・耐食性の低下が効果的に抑制される。 When the porous material layer 352 contains metal fibers (particularly when the porous material layer 352 is made of metal fibers), the coverage is preferably 50% or more. That is, it is preferable to cover 50% or more of the surface of the porous material layer 352 containing metal fibers with “conductive carbon”. Further, it is more preferably 80% or more, further preferably 90% or more, and most preferably 100%. By adopting such a configuration, a decrease in conductivity and corrosion resistance due to the formation of an oxide film on the exposed portion of the porous material layer 352 that is not covered with the conductive carbon layer 354 is effectively suppressed.
　一方、多孔質材料層３５２が炭素繊維を含む場合（特に多孔質材料層３５２が炭素繊維からなる場合）、導電性炭素層３５４による多孔質材料層３５２の被覆率は、好ましくは８５％以上である。また、より好ましくは９０％以上であり、最も好ましくは９２％である。このような構成とすることにより、特に前記炭素繊維がＰＡＮ系もしくはピッチ系炭素繊維である場合には、黒鉛化された炭素繊維で構成される多孔質材料と同程度の接触抵抗を確保できる。 On the other hand, when the porous material layer 352 contains carbon fibers (particularly when the porous material layer 352 is made of carbon fibers), the coverage of the porous material layer 352 by the conductive carbon layer 354 is preferably 85% or more. is there. Further, it is more preferably 90% or more, and most preferably 92%. By adopting such a configuration, particularly when the carbon fiber is a PAN-based or pitch-based carbon fiber, it is possible to ensure contact resistance comparable to that of a porous material composed of graphitized carbon fiber.
　なお、本実施形態のように、後述する中間層３５６が多孔質材料層３５２と導電性炭素層３５４との間に介在する場合、上記被覆率は、ガス拡散層４を積層方向から見た場合に、導電性炭素層３５４と重複する多孔質材料層３５２の面積の割合を意味する。 Note that, when the intermediate layer 356 described later is interposed between the porous material layer 352 and the conductive carbon layer 354 as in the present embodiment, the above coverage is obtained when the gas diffusion layer 4 is viewed from the stacking direction. Furthermore, the ratio of the area of the porous material layer 352 overlapping the conductive carbon layer 354 is meant.
　［中間層］
　まず第１として、上述の図３４に示すように、本実施形態における導電性炭素層３５４は多孔質材料層３５２の表面上に存在し、導電性炭素層３５４と多孔質材料層３５２との間に、金属で構成される中間層３５６をさらに有しても良い。次に第２として、多孔質材料層３５２及び導電性炭素層３５４の少なくとも一方の内部に前記金属が存在しても良い（図示せず）。 [Middle layer]
First, as shown in FIG. 34 described above, the conductive carbon layer 354 in the present embodiment is present on the surface of the porous material layer 352, and between the conductive carbon layer 354 and the porous material layer 352. In addition, an intermediate layer 356 made of metal may be further included. Second, the metal may be present in at least one of the porous material layer 352 and the conductive carbon layer 354 (not shown).
　本実施形態のＧＤＬは、導電体として中間層３５６を有しても良い。中間層３５６は、多孔質材料層３５２と導電性炭素層３５４との密着性を向上させるという機能や、多孔質材料層３５２からのイオンの溶出を防止するという機能を有する。特に、Ｒ値が上述した好ましい範囲の上限値を超える場合に、中間層３５６を設けることによる効果は顕著に発現する。ただし、Ｒ値が上述した好ましい範囲に含まれる場合であっても中間層を設けても良い。他の観点からは、中間層３５６の設置による作用効果は、多孔質材料層３５２がアルミニウム又はその合金から構成される場合にも顕著に発現する。なお、本実施形態において、中間層は任意の層であり、必ずしも中間層は存在しなくても良い。以下、中間層を含む場合の好ましい形態について簡単に説明する。 The GDL of this embodiment may include an intermediate layer 356 as a conductor. The intermediate layer 356 has a function of improving adhesion between the porous material layer 352 and the conductive carbon layer 354 and a function of preventing elution of ions from the porous material layer 352. In particular, when the R value exceeds the upper limit value of the preferable range described above, the effect of providing the intermediate layer 356 is remarkably exhibited. However, the intermediate layer may be provided even when the R value is included in the above-described preferable range. From another point of view, the function and effect of the intermediate layer 356 can be significantly exhibited even when the porous material layer 352 is made of aluminum or an alloy thereof. In the present embodiment, the intermediate layer is an arbitrary layer, and the intermediate layer does not necessarily exist. Hereinafter, a preferable form in the case of including an intermediate layer will be briefly described.
　中間層３５６を構成する材料としては、密着性を付与するものであれば特に制限はないが、第一実施形態の中間層３２と同様の材料を使用することができる。特に、上述したイオン溶出の少ない金属又はその炭化物もしくは窒化物を用いた場合、多孔質材料層の耐食性を有意に向上させることができる。さらに、中間層３５６の構造も特に制限されないが、第一実施形態の中間層３２と同様の柱状構造とすることができる。 The material constituting the intermediate layer 356 is not particularly limited as long as it provides adhesion, but the same material as that of the intermediate layer 32 of the first embodiment can be used. In particular, when the above-described metal with little ion elution or a carbide or nitride thereof is used, the corrosion resistance of the porous material layer can be significantly improved. Further, the structure of the intermediate layer 356 is not particularly limited, but can be a columnar structure similar to the intermediate layer 32 of the first embodiment.
　中間層３５６の厚さは、０.００５μｍ～１０μｍであることが好ましく、０.００５μｍ～０．１μｍであることがより好ましく、０.００５μｍ～０．０１μｍであることがさらに好ましい。中間層自体は導電性炭素層と繊維間の熱膨張による剥離を抑えることや、繊維を構成する金属の耐食性が弱い場合の防食という点で効果がある。１０μｍ以上では中間層の厚さによって多孔質層の空孔が閉塞する可能性が高くなり、０．００５μｍ以下は、分光学的な計測手段で精度の良い結果が得られる下限以下になる。なお、前記中間層の厚さは、ＡＥＳの深さ分析により計測することができる。 The thickness of the intermediate layer 356 is preferably 0.005 μm to 10 μm, more preferably 0.005 μm to 0.1 μm, and still more preferably 0.005 μm to 0.01 μm. The intermediate layer itself is effective in terms of suppressing peeling due to thermal expansion between the conductive carbon layer and the fiber, and preventing corrosion when the metal constituting the fiber has low corrosion resistance. When the thickness is 10 μm or more, there is a high possibility that the pores of the porous layer are clogged depending on the thickness of the intermediate layer. The thickness of the intermediate layer can be measured by AES depth analysis.
　また、中間層３５６の、導電性炭素層３５４側の表面は、ナノレベルで粗れていることが好ましい。このような形態によれば、中間層３５６上に成膜される導電性炭素層３５４の、中間層３５６に対する密着性をより一層向上させる。 Also, the surface of the intermediate layer 356 on the conductive carbon layer 354 side is preferably rough at the nano level. According to such a configuration, the adhesion of the conductive carbon layer 354 formed on the intermediate layer 356 to the intermediate layer 356 is further improved.
　さらに、中間層３５６の熱膨張率が、多孔質材料層３５２を構成する金属の熱膨張率と近い値であると、中間層３５６と多孔質材料層３５２との密着性は向上する。ただし、このような形態では中間層３５６と導電性炭素層３５４との密着性が低下する場合がある。同様に、中間層３５６の熱膨張率が導電性炭素層３５４の熱膨張率と近い値であると、中間層３５６と多孔質材料層３５２との密着性が低下する場合がある。これらを考慮して、中間層の熱膨張率（αｍｉｄ）、多孔質材料層の熱膨張率（αｓｕｂ）、及び導電性炭素層の熱膨張率を（αｃ）は、下記関係を満足することが好ましい。なお、αｓｕｂとαｍｉｄとが同一の値である場合とは、多孔質材料層の金属繊維の構成金属と、中間層の構成金属とが共に同一である場合に相当する。 Furthermore, when the thermal expansion coefficient of the intermediate layer 356 is a value close to the thermal expansion coefficient of the metal constituting the porous material layer 352, the adhesion between the intermediate layer 356 and the porous material layer 352 is improved. However, in such a form, the adhesion between the intermediate layer 356 and the conductive carbon layer 354 may decrease. Similarly, when the thermal expansion coefficient of the intermediate layer 356 is close to the thermal expansion coefficient of the conductive carbon layer 354, the adhesion between the intermediate layer 356 and the porous material layer 352 may be reduced. Considering these, the thermal expansion coefficient (α mid ) of the intermediate layer, the thermal expansion coefficient (α sub ) of the porous material layer, and the thermal expansion coefficient (α c ) of the conductive carbon layer satisfy the following relationship: It is preferable to do. The case where α sub and α mid are the same value corresponds to the case where the constituent metal of the metal fiber of the porous material layer and the constituent metal of the intermediate layer are the same.
［数５］
αｓｕｂ ≧ αｍｉｄ ＞ αｃ [Equation 5]
α sub ≧ α mid > α c
　なお、中間層３５６は、多孔質材料層３５２の少なくとも一方の表面上に存在すれば良い。また、導電性炭素層が多孔質材料層の両面に存在する場合には、中間層は、多孔質材料層と双方の導電性炭素層との間にそれぞれ介在することが好ましい。多孔質材料層といずれか一方の導電性炭素層との間にのみ中間層が存在する場合には、当該中間層は、セパレータ側に配置されることとなる導電性炭素層と多孔質材料層との間に存在することが好ましい。 Note that the intermediate layer 356 may be present on at least one surface of the porous material layer 352. Moreover, when a conductive carbon layer exists in both surfaces of a porous material layer, it is preferable to interpose an intermediate | middle layer between a porous material layer and both conductive carbon layers, respectively. When an intermediate layer exists only between the porous material layer and one of the conductive carbon layers, the intermediate layer is disposed on the separator side. The conductive carbon layer and the porous material layer It is preferable that it exists between.
　［親水化層］
　上述のように、導電性炭素層３５４は、多孔質材料層３５２の表面上に存在しても良い。かかる場合、図３４に示すように、導電性炭素層３５４上に金属、金属窒化物、金属炭化物及び金属酸化物よりなる群から選択される一種以上で構成される親水化層３５８をさらに有しても良い。そして、親水化層３５８は、セパレータと向かい合う側に存在する導電性炭素層上に、セパレータと隣接する状態で配置されることが好ましい。図１で示すならば、親水化層は、ガス拡散層（４ａ、４ｂ）のうち、セパレータ（５ａ、５ｂ）が存在する側の表面に配置されることが好ましい。このような親水化層の機能について以下に説明する。電池の発電によって水が発生するが、この水は速やかにセパレータへと運ばれて排出されることが極めて望ましい。その際、親水化層がガス拡散層（４ａ、４ｂ）のうち、セパレータ（５ａ、５ｂ）が存在する側の表面に配置されていると、セパレータの界面における親水性が向上して、触媒層（３ａ、３ｂ）からセパレータ側への速やかな水の排出を促進できる。 [Hydrophilic layer]
As described above, the conductive carbon layer 354 may exist on the surface of the porous material layer 352. In such a case, as shown in FIG. 34, the conductive carbon layer 354 further includes a hydrophilic layer 358 composed of one or more selected from the group consisting of metals, metal nitrides, metal carbides, and metal oxides. May be. And it is preferable that the hydrophilization layer 358 is arrange | positioned in the state adjacent to a separator on the conductive carbon layer which exists in the side facing a separator. If it shows in FIG. 1, it is preferable to arrange | position a hydrophilization layer on the surface of the side in which a separator (5a, 5b) exists among gas diffusion layers (4a, 4b). The function of such a hydrophilic layer will be described below. Although water is generated by the power generation of the battery, it is highly desirable that this water be quickly transported to the separator and discharged. At that time, if the hydrophilic layer is disposed on the surface of the gas diffusion layer (4a, 4b) where the separator (5a, 5b) is present, the hydrophilicity at the separator interface is improved, and the catalyst layer Rapid discharge of water from (3a, 3b) to the separator side can be promoted.
　図１において、セパレータ（５ａ、５ｂ）に存在する複数の凹部によって構成される溝状の流路が排水に関与する。そのため、セパレータ（５ａ、５ｂ）側のガス拡散層（４ａ、４ｂ）の親水化層のうち、前記凹部と接する親水化層の部分は、高い親水度を有するようにするために、金属で構成されることが好ましい。一方、前記凸部と接する親水化層の部分は、親水性は重要でないといえるため、金属、金属窒化物、金属炭化物及び金属酸化物よりなる群から選択される一種以上で構成されれば良い。さらにいえば、前記凸部と接する親水化層の部分にはこのような親水化層は存在しなくても良い。かかる場合、親水化層は、ガス拡散層の面上に存在する部分的な（不連続的な）「層」形態を採ることができる。 In FIG. 1, a groove-like flow path constituted by a plurality of recesses present in the separators (5a, 5b) is involved in drainage. Therefore, in the hydrophilic layer of the gas diffusion layer (4a, 4b) on the separator (5a, 5b) side, the portion of the hydrophilic layer in contact with the recess is made of metal so as to have a high degree of hydrophilicity. It is preferred that On the other hand, the portion of the hydrophilic layer in contact with the convex portion may be composed of one or more selected from the group consisting of metals, metal nitrides, metal carbides, and metal oxides because hydrophilicity is not important. . Furthermore, such a hydrophilized layer may not be present in a portion of the hydrophilized layer in contact with the convex portion. In such a case, the hydrophilization layer may take the form of a partial (discontinuous) “layer” that exists on the surface of the gas diffusion layer.
　親水化層を構成する金属は、貴金属、セパレータを構成する金属元素、及びセパレータの表面処理に含まれる金属元素よりなる群から選択される一種以上を含有しても良い。貴金属としては、導電性炭素層３５４中に含まれうる貴金属を挙げることができる。セパレータを構成する金属元素としては、例えば、鉄、チタン、アルミニウム及び銅並びにこれらの合金が挙げられる。これらの合金としては、上記金属繊維を構成するステンレス等の合金が挙げられる。セパレータの表面処理に含まれる金属元素としては、第一～第三実施形態で使用した元素を挙げることができる。前記金属が貴金属であると、親水化向上のみならず、接触抵抗を有意に低下できる。また、前記金属がセパレータを構成する金属元素や、セパレータの表面処理に含まれる金属元素であると、異種金属同士が接する場合に生じる腐食を効果的に防止できる。なお、金属窒化物、金属炭化物や金属酸化物は、上記した金属の窒化物、炭化物や酸化物の全てを含むことができる。 The metal constituting the hydrophilic layer may contain one or more selected from the group consisting of noble metals, metal elements constituting the separator, and metal elements included in the surface treatment of the separator. As the noble metal, a noble metal that can be included in the conductive carbon layer 354 can be given. As a metallic element which comprises a separator, iron, titanium, aluminum, copper, and these alloys are mentioned, for example. Examples of these alloys include alloys such as stainless steel constituting the metal fibers. Examples of the metal element contained in the surface treatment of the separator include the elements used in the first to third embodiments. When the metal is a noble metal, not only can hydrophilicity be improved, but contact resistance can be significantly reduced. In addition, when the metal is a metal element constituting the separator or a metal element included in the surface treatment of the separator, corrosion that occurs when different kinds of metals come into contact with each other can be effectively prevented. The metal nitride, metal carbide, and metal oxide can include all of the above-described metal nitride, carbide, and oxide.
　図３４には、親水化層３５８を示している。図３４では、一例として、親水化層３５８を連続的な層として表しているが、不連続な層形態、即ち上述したような金属の分散した層形態を採っても良い。また、図３４では、導電体として、多孔質材料層３５２及び導電性炭素層３５４並びに任意の中間層３５６及び親水化層３５８が存在している。しかし、本実施形態において、中間層３５６及び親水化層３５８は、いずれも存在しなくて良いし、少なくともいずれか一方が存在していても良い。 FIG. 34 shows the hydrophilic layer 358. In FIG. 34, as an example, the hydrophilized layer 358 is shown as a continuous layer. However, a discontinuous layer form, that is, a metal dispersed layer form as described above may be employed. In FIG. 34, a porous material layer 352, a conductive carbon layer 354, an optional intermediate layer 356, and a hydrophilic layer 358 are present as conductors. However, in the present embodiment, neither the intermediate layer 356 nor the hydrophilic layer 358 may be present, and at least one of them may be present.
　ここで、図３４におけるガス拡散層の断面図は、多孔質材料層の上に中間層及び導電性炭素層が積層された構造を示している。しかし、本実施形態の断面図はこれに限られず、繊維で構成される多孔質材料層の内部に中間層及び導電性炭素層が「積層」された構造であっても良い。ただ、親水化層の機能はセパレータ側への水の排出を促進することにあるため、導電性炭素層及び中間層が多孔質材料層のどの位置に設けられたしても、親水化層は多孔質材料層の上に存在することが好ましい。 Here, the cross-sectional view of the gas diffusion layer in FIG. 34 shows a structure in which an intermediate layer and a conductive carbon layer are laminated on the porous material layer. However, the cross-sectional view of the present embodiment is not limited to this, and may have a structure in which an intermediate layer and a conductive carbon layer are “laminated” inside a porous material layer composed of fibers. However, since the function of the hydrophilic layer is to promote discharge of water to the separator side, the hydrophilic layer does not matter where the conductive carbon layer and the intermediate layer are provided in the porous material layer. It is preferably present on the porous material layer.
　本実施形態のガス拡散層は、その厚さ方向の電気抵抗値が１ｍΩ・ｃｍ２以下であることが好ましい。ガス拡散層の厚さ方向の電気抵抗値が２．０ｍΩ以下の場合、電池性能が上昇しやすくなる上に、発熱によるガス拡散層の構成成分の脆化を効果的に防止できる。ここで、厚さ方向の電気抵抗値とは、金メッキした２枚の５０ｍｍ角（厚さ１０ｍｍ）の試験用電極でガス拡散層を圧力１ＭＰａで挟み、両試験用電極間で測定した電気抵抗値（ｍΩ）のことである。 The gas diffusion layer of the present embodiment preferably has an electric resistance value in the thickness direction of 1 mΩ · cm 2 or less. When the electric resistance value in the thickness direction of the gas diffusion layer is 2.0 mΩ or less, the battery performance is easily improved, and embrittlement of the components of the gas diffusion layer due to heat generation can be effectively prevented. Here, the electric resistance value in the thickness direction is an electric resistance value measured between two test electrodes with a gas diffusion layer sandwiched between two gold-plated 50 mm square test electrodes (thickness 10 mm) at a pressure of 1 MPa. (MΩ).
　本実施形態のガス拡散層は、その厚さを１００μｍ～３００μｍとすることができるが、セルの形状や性能を鑑みて適宜厚さを調整することができる。また、上記ガス拡散層においては、繊維成分が導電性を有する上、繊維同士が互いに融着するため、当該ガス拡散層の導電性も高くなる。 The thickness of the gas diffusion layer of this embodiment can be set to 100 μm to 300 μm, but the thickness can be appropriately adjusted in view of the shape and performance of the cell. Moreover, in the said gas diffusion layer, since a fiber component has electroconductivity, since fiber mutually fuse | melts, the electroconductivity of the said gas diffusion layer also becomes high.
　次に、ガス拡散層を製造するための好ましい実施形態を記載するが、本発明の技術的範囲は下記の形態のみには限定されない。また、ガス拡散層を構成する各部材の材質などの諸条件については、上述した通りであるため、ここでは説明を省略する。 Next, preferred embodiments for producing the gas diffusion layer will be described, but the technical scope of the present invention is not limited to the following embodiments. In addition, since various conditions such as the material of each member constituting the gas diffusion layer are as described above, the description thereof is omitted here.
　本実施形態に係る燃料電池用ガス拡散層の製造方法は、多孔質材料層の表面上又は内部に、導電性炭素層又は導電性炭素粒子を形成する工程を含む。なお、多孔質材料層については、市販品を用いることができる。しかし、本実施形態における多孔質材料層の中には、例えば、黒鉛化処理を施さないＰＡＮ系もしくはピッチ系炭素繊維のように、現状では市販品として流通していないようなものもある。そこで、上記の特殊なＰＡＮ系もしくはピッチ系炭素繊維については、その製造方法や条件について後述する。 The method for producing a fuel cell gas diffusion layer according to the present embodiment includes a step of forming a conductive carbon layer or conductive carbon particles on or in the surface of the porous material layer. In addition, about a porous material layer, a commercial item can be used. However, some of the porous material layers in the present embodiment are not currently distributed as commercial products, such as PAN-based or pitch-based carbon fibers that are not graphitized. Therefore, the manufacturing method and conditions of the special PAN-based or pitch-based carbon fiber will be described later.
　前記導電性炭素層又は導電性炭素粒子を形成する工程（１）は、導電性の炭素（例えば、グラファイト）をターゲットとして、多孔質材料層上に導電性炭素を含む層を原子レベルで積層する。これにより、導電性炭素層を形成することができる。このようにして、直接付着した導電性炭素層と多孔質材料層との界面及びその近傍は、分子間力や僅かな炭素原子の進入によって、長期間にわたって密着性が保持される。 In the step (1) of forming the conductive carbon layer or the conductive carbon particles, a layer containing conductive carbon is stacked on the porous material layer at the atomic level using conductive carbon (for example, graphite) as a target. . Thereby, a conductive carbon layer can be formed. In this way, the adhesion between the directly adhered conductive carbon layer and the porous material layer and the vicinity thereof is maintained for a long period of time due to intermolecular forces and the entry of a few carbon atoms.
　導電性炭素を積層するのに好適な手法として、例えば、スパッタリング法もしくはイオンプレーティング法などのＰＶＤ法、又はＦＣＶＡ法等のイオンビーム蒸着法等が挙げられる。スパッタリング法としては、マグネトロンスパッタリング法、ＵＢＭＳ法、デュアルマグネトロンスパッタ法、ＥＣＲスパッタリング法などが挙げられる。また、イオンプレーティング法としては、アークイオンプレーティング法などが挙げられる。なかでも、スパッタリング法及びイオンプレーティング法を用いることが好ましく、スパッタリング法を用いることが特に好ましい。このような手法によれば、水素含有量の少ない炭素層を形成することができる。その結果、炭素原子同士の結合（ｓｐ２混成炭素）の割合を増加させることができ、優れた導電性が達成される。これに加えて、比較的低温で成膜が可能であり、多孔質材料層へのダメージを最小限に抑えることができるという利点もある。さらに、スパッタリング法によれば、バイアス電圧等を制御することで、成膜される層の膜質をコントロールできる。また、導電性炭素層をスパッタリング法によって形成することにより、連続的かつ効率的に導電性炭素層を製造できる。 As a method suitable for laminating conductive carbon, for example, a PVD method such as a sputtering method or an ion plating method, an ion beam evaporation method such as an FCVA method, or the like can be given. Examples of the sputtering method include a magnetron sputtering method, a UBMS method, a dual magnetron sputtering method, and an ECR sputtering method. Examples of the ion plating method include an arc ion plating method. Especially, it is preferable to use sputtering method and an ion plating method, and it is especially preferable to use sputtering method. According to such a method, a carbon layer having a low hydrogen content can be formed. As a result, the ratio of bonds between carbon atoms (sp 2 hybrid carbon) can be increased, and excellent conductivity is achieved. In addition, there is an advantage that the film can be formed at a relatively low temperature, and damage to the porous material layer can be minimized. Further, according to the sputtering method, the film quality of the deposited layer can be controlled by controlling the bias voltage and the like. Moreover, a conductive carbon layer can be manufactured continuously and efficiently by forming a conductive carbon layer by sputtering method.
　なお、多孔質材料層が金属繊維を含むような場合、アルゴン（Ａｒ）プラズマによるスパッタによって、多孔質材料層（金属繊維）表面の酸化皮膜を除去しておくことが好ましい。 When the porous material layer contains metal fibers, it is preferable to remove the oxide film on the surface of the porous material layer (metal fibers) by sputtering with argon (Ar) plasma.
　図３７は、スパッタリング法を用いた中間層や導電性炭素層の成膜装置を示す概略図である。導電性炭素層の成膜をスパッタリング法により行う場合、チャンバ３６４の真空度が３～１０Ｐａ程度になるように、ガス排気口３６６より排気することが好ましい。その後、好ましくはＡｒを０．１～１Ｐａ程度、雰囲気ガス導入口３６８より導入する。ガス拡散層自体の温度は、室温（２５℃）～２００℃程度の範囲であれば特に制限されないが、好ましくは、ＧＤＬ（特に多孔質材料層）の材質に応じて温度を設定する。そして、スパッタリングは、ターゲット３７０から多孔質材料層３７２へとターゲット材料（Ｃｒや黒鉛など）をはじき出すことにより行う。 FIG. 37 is a schematic view showing a film forming apparatus for an intermediate layer and a conductive carbon layer using a sputtering method. When the conductive carbon layer is formed by sputtering, it is preferable to exhaust the gas through the gas exhaust port 366 so that the degree of vacuum in the chamber 364 is about 3 to 10 Pa. Thereafter, Ar is introduced preferably through the atmospheric gas inlet 368 at about 0.1 to 1 Pa. The temperature of the gas diffusion layer itself is not particularly limited as long as it is in the range of room temperature (25 ° C.) to 200 ° C., but preferably the temperature is set according to the material of GDL (particularly the porous material layer). Sputtering is performed by ejecting a target material (such as Cr or graphite) from the target 370 to the porous material layer 372.
　ここで、導電性炭素層の成膜をスパッタリング法により行う場合には、スパッタリング時に多孔質材料層に対して負のバイアス電圧を印加すると良い。このような形態によれば、イオン照射効果によって、グラファイトクラスタが緻密に集合した構造の導電性炭素層が成膜される。このような導電性炭素層は優れた導電性を発揮することから、他の部材（例えば、触媒層やセパレータ）との接触抵抗の小さいガス拡散層が提供される。印加される負のバイアス電圧の大きさ（絶対値）は特に制限されず、導電性炭素層を成膜可能な電圧が採用される。一例として、印加される電圧の大きさは、好ましくは５０～５００Ｖであり、より好ましくは１００～３００Ｖである。なお、成膜時のその他の条件等の具体的な形態は特に制限されない。また、ＵＢＭＳ法により導電性炭素層３５４を成膜する場合には、予め中間層を形成しておき、その上に導電性炭素層を形成することが好ましい。これにより、下地層との密着性に優れる導電性炭素層が形成される。ただし、他の手法によって導電性炭素層を形成する場合には、中間層が存在しない場合であっても、多孔質材料層との密着性に優れる導電性炭素層が形成される。 Here, when the conductive carbon layer is formed by sputtering, a negative bias voltage may be applied to the porous material layer during sputtering. According to such a form, the conductive carbon layer having a structure in which graphite clusters are densely assembled is formed by the ion irradiation effect. Since such a conductive carbon layer exhibits excellent conductivity, a gas diffusion layer having a low contact resistance with other members (for example, a catalyst layer or a separator) is provided. The magnitude (absolute value) of the negative bias voltage to be applied is not particularly limited, and a voltage capable of forming a conductive carbon layer is employed. As an example, the magnitude of the applied voltage is preferably 50 to 500V, more preferably 100 to 300V. Note that there are no particular restrictions on specific forms such as other conditions during film formation. In addition, when the conductive carbon layer 354 is formed by the UBMS method, it is preferable to form an intermediate layer in advance and form the conductive carbon layer thereon. Thereby, the electroconductive carbon layer excellent in adhesiveness with a base layer is formed. However, when the conductive carbon layer is formed by another method, a conductive carbon layer having excellent adhesion to the porous material layer is formed even when the intermediate layer is not present.
　上述した手法によれば、多孔質材料層３５２の一方の表面に導電性炭素層３５４が形成されたガス拡散層が製造される。多孔質材料層３５２の両面に導電性炭素層３５４が形成されたガス拡散層を製造するには、多孔質材料層３５２の他方の表面に対して、上述したのと同様の手法によって、導電性炭素層を形成すれば良い。 According to the above-described method, a gas diffusion layer in which the conductive carbon layer 354 is formed on one surface of the porous material layer 352 is manufactured. In order to manufacture the gas diffusion layer in which the conductive carbon layer 354 is formed on both surfaces of the porous material layer 352, the other surface of the porous material layer 352 is made conductive by the same method as described above. A carbon layer may be formed.
　図３４に示すような、中間層３５６を有するガス拡散層を製造するには、上述した導電性炭素層の成膜工程の前に、多孔質材料層の少なくとも一方の表面に中間層を成膜する工程を行う。この際、中間層を成膜する手法としては、導電性炭素層の成膜について上述したのと同様の手法が採用される。ただし、ターゲットを中間層の構成材料に変更する必要がある。 In order to manufacture the gas diffusion layer having the intermediate layer 356 as shown in FIG. 34, the intermediate layer is formed on at least one surface of the porous material layer before the conductive carbon layer forming step described above. The process to do is performed. At this time, as the method for forming the intermediate layer, the same method as described above for the formation of the conductive carbon layer is employed. However, it is necessary to change the target to the constituent material of the intermediate layer.
　続いて、上記工程により成膜された中間層上に、導電性炭素層を成膜すれば良い。中間層の表面に導電性炭素層を成膜する手法も、多孔質材料層の表面への導電性炭素層の成膜について上述したのと同様の手法が採用される。 Subsequently, a conductive carbon layer may be formed on the intermediate layer formed by the above process. As the method for forming the conductive carbon layer on the surface of the intermediate layer, the same method as described above for the formation of the conductive carbon layer on the surface of the porous material layer is employed.
　また、工程（１）の後に、親水化層を形成する工程（２）を行っても良い。工程（２）としては、金属、金属窒化物、金属炭化物及び金属酸化物よりなる群から選択される一種以上をターゲットとするスパッタ法や、金属のメッキ処理を用いることができる。セパレータと向かい合う側のガス拡散層の表面に親水化層を形成する際、所定の金属などをスパッタリングすることによって、工程（１）から工程（２）までを簡易かつ連続的に行うことができる。一方、工程（２）をメッキ処理によって行う場合に、多孔質材料層が連続したシート状であると、溶液中においてＲｏｌｌ－ｔｏ－Ｒｏｌｌ方式で処理できるため、効率的かつ低コストで製造できる。 Further, after the step (1), a step (2) of forming a hydrophilic layer may be performed. As the step (2), a sputtering method that targets at least one selected from the group consisting of metals, metal nitrides, metal carbides, and metal oxides, and metal plating can be used. When forming the hydrophilic layer on the surface of the gas diffusion layer facing the separator, the steps (1) to (2) can be performed easily and continuously by sputtering a predetermined metal or the like. On the other hand, when the step (2) is carried out by plating, if the porous material layer is a continuous sheet, it can be processed in a roll-to-roll method in a solution, and therefore can be manufactured efficiently and at low cost.
　また、工程の順序について言及すると、工程（１）の後に工程（２）を行うことにより、所望のガス拡散層を形成できる。一方、工程（１）と工程（２）をほぼ同時に行うことによっても、ガス拡散層のセパレータ側表面に親水化層を形成することができ、さらには製造時間の大幅な短縮という利点がある。なお、同時に行う場合、親水化層を構成する親水化材料はガス拡散層のセパレータ側表面のみならず、ガス拡散層全体に存在することになる。しかし、上述ように、親水化層は不連続な層形態、すなわち金属が分散した層形態を採っても良い。したがって、製造時間の大幅な短縮に起因するコストや労力の低減という利点を考慮すれば、工程（１）と工程（２）を同時（殆ど同時）に行うことの意義は十分にあるといえる。 Further, referring to the order of steps, a desired gas diffusion layer can be formed by performing step (2) after step (1). On the other hand, even if the step (1) and the step (2) are performed almost simultaneously, a hydrophilic layer can be formed on the separator-side surface of the gas diffusion layer, and further, there is an advantage that the manufacturing time is greatly shortened. In addition, when performing simultaneously, the hydrophilization material which comprises a hydrophilization layer exists in not only the separator side surface of a gas diffusion layer but the whole gas diffusion layer. However, as described above, the hydrophilic layer may take a discontinuous layer form, that is, a layer form in which a metal is dispersed. Therefore, it can be said that it is sufficiently meaningful to perform the steps (1) and (2) at the same time (almost at the same time) in view of the advantages of cost and labor reduction due to the significant shortening of the manufacturing time.
　前記メッキ処理の際に用いられる金属は、貴金属又はセパレータを構成する金属元素であることが好ましい。前記金属が貴金属であると、親水化向上のみならず、接触抵抗を有意に低下できる。また、前記金属がセパレータを構成する金属元素であると、異種金属同士が接する場合に生じる腐食を効果的に防止できる。 The metal used in the plating process is preferably a noble metal or a metal element constituting a separator. When the metal is a noble metal, not only can hydrophilicity be improved, but contact resistance can be significantly reduced. Further, when the metal is a metal element constituting the separator, it is possible to effectively prevent the corrosion that occurs when different metals come into contact with each other.
　上記の工程（１）及び工程（２）を以下のように換言することができる。まず、スパッタ法を用いて、導電性炭素層もしくは導電性炭素粒子、及び／又は親水化層を形成することができる。一方、親水化層の形成については、スパッタ法の代わりにメッキ処理を用いることができる。 The above step (1) and step (2) can be rephrased as follows. First, a conductive carbon layer or conductive carbon particles and / or a hydrophilic layer can be formed by sputtering. On the other hand, for the formation of the hydrophilic layer, a plating process can be used instead of the sputtering method.
　上述のように、ポリアクリロニトリル系もしくはピッチ系炭素繊維を製造することにより多孔質材料層を得ようとする際、黒鉛化処理まで行わずに炭素化処理で終了することが好ましい。これにより、コストの大幅な削減をもたらされる。図３８は、一般的なＰＡＮ系炭素繊維の製造工程及び本実施形態におけるＰＡＮ系炭素繊維の製造工程を示す図である。図３８中、本実施形態では黒鉛化処理を行わない点に最大の特徴がある。図３８のフローチャートより簡潔に言えば、炭素化処理後、黒鉛化処理を行うことなく表面処理やサイジングからなる仕上げ（フィラメントの切断）処理を行う。この処理により得られたチョップドファイバを抄紙化する際、好ましくはファイバの表面を従来公知のフッ素系液体を用いて撥水処理加工を行う。そして、最後に焼成してガス拡散層のロール状シートを得ることができる。本実施形態における特殊なＰＡＮ系炭素繊維の各製造工程の方法や条件については、図３８に示すような従来公知のものを適用すれば良い。以下、本実施形態におけるＰＡＮ系炭素繊維の各製造工程の方法や条件の一例を示すが、本発明におけるＰＡＮ系炭素繊維の製造方法は以下に制限されることはなく、適宜方法や条件の変更等を行っても良い。 As described above, when a porous material layer is to be obtained by producing a polyacrylonitrile-based or pitch-based carbon fiber, it is preferable to end the carbonization without performing graphitization. This results in a significant cost reduction. FIG. 38 is a diagram showing a general PAN-based carbon fiber manufacturing process and a PAN-based carbon fiber manufacturing process in the present embodiment. In FIG. 38, this embodiment has the greatest feature in that no graphitization is performed. To put it more succinctly than the flowchart of FIG. 38, after the carbonization treatment, a finishing (filament cutting) treatment including surface treatment and sizing is performed without performing graphitization treatment. When the chopped fiber obtained by this treatment is made into paper, the surface of the fiber is preferably subjected to a water-repellent treatment using a conventionally known fluorine-based liquid. And it can calcinate at the end and can obtain the roll-shaped sheet of a gas diffusion layer. As a method and conditions for each manufacturing process of the special PAN-based carbon fiber in the present embodiment, a conventionally known one as shown in FIG. 38 may be applied. Hereinafter, although an example of the method and conditions of each manufacturing process of the PAN-based carbon fiber in the present embodiment will be shown, the manufacturing method of the PAN-based carbon fiber in the present invention is not limited to the following, and the method and conditions are appropriately changed. Etc. may be performed.
　まず、アクリロニトリルを主成分とする単量体を重合してＰＡＮ系重合体を得る。続いて、ＰＡＮ系重合体を湿式及び／又は乾式により紡糸してＰＡＮ系前駆体繊維を製造する。 First, a monomer mainly composed of acrylonitrile is polymerized to obtain a PAN-based polymer. Subsequently, the PAN-based polymer is spun by wet and / or dry processes to produce PAN-based precursor fibers.
　ＰＡＮ系重合体は、単量体のうち主成分であるアクリロニトリルを、好ましくは９０重量％以上、より好ましくは９５重量％以上含有する。なお、必要に応じて、アクリロニトリルと共重合可能なその他の単量体を加えて共重合しても良い。紡糸に際し、前記重合体及び共重合体を溶媒又は水溶液に溶解させることにより紡糸原液とする。なお、その他の単量体としては、アクリロニトリルと共重合可能なものであれば特に限定されないが、ブタジエン、スチレン等が挙げられる。 The PAN polymer preferably contains 90% by weight or more, more preferably 95% by weight or more of acrylonitrile, which is the main component of the monomers. If necessary, other monomers copolymerizable with acrylonitrile may be added for copolymerization. In spinning, the polymer and copolymer are dissolved in a solvent or an aqueous solution to obtain a spinning dope. The other monomer is not particularly limited as long as it is copolymerizable with acrylonitrile, and examples thereof include butadiene and styrene.
　上記紡糸原液の溶媒としては、ジメチルスルホキシド、ジメチルホルムアミド、ジメチルアセトアミドやＮ－メチルピロリドン等の有機系溶媒が挙げられる。また、紡糸原液の水溶液としては、塩化亜鉛水溶液やチオシアン酸ナトリウム水溶液等が挙げられる。 Examples of the solvent for the spinning dope include organic solvents such as dimethyl sulfoxide, dimethylformamide, dimethylacetamide and N-methylpyrrolidone. Moreover, examples of the aqueous solution of the spinning dope include a zinc chloride aqueous solution and a sodium thiocyanate aqueous solution.
　かかる紡糸原液は、一般に、湿式及び／又は乾式により紡糸して繊維化する。必要により加圧スチームなどの熱媒中で延伸して、配向を調整たり、場合によっては１３０～２００℃の熱処理をさらに施し、巻き取ってＰＡＮ系前駆体繊維を得ることができる。なお、前記ＰＡＮ系前駆体繊維の基本骨格は図３６の（ａ）に示している。 Such spinning dope is generally spun into fibers by wet and / or dry methods. If necessary, the film is stretched in a heating medium such as pressurized steam to adjust the orientation, or in some cases, further subjected to heat treatment at 130 to 200 ° C. and wound to obtain a PAN-based precursor fiber. The basic skeleton of the PAN-based precursor fiber is shown in FIG.
　続いて、ＰＡＮ系前駆体繊維から、本実施形態におけるＰＡＮ系炭素繊維を製造する。まず、ＰＡＮ系前駆体繊維を安定化処理する。安定化処理では、空気などの酸化性雰囲気中、好ましくは２００～３５０℃、より好ましくは２００～３００℃、さらに好ましくは２３０～２７０℃で加熱しつつ、０．９５～１．０５倍に延伸する。これにより、ＰＡＮ系前駆体繊維を耐炎化繊維へと変換させる。その際、処理時間は８０～１６０分であり、加圧度は例えば１．３ｇ／ｃｍ３超である。なお、前記耐炎化繊維の基本骨格は図３６の（ｂ）に示している。その後、任意の段階として、得られた耐炎化繊維を、空気などの酸化性雰囲気中、好ましくは８００～１２００℃で加熱しつつ賦活化することにより活性炭素繊維を得る。 Subsequently, the PAN-based carbon fiber in the present embodiment is manufactured from the PAN-based precursor fiber. First, the PAN precursor fiber is subjected to stabilization treatment. In the stabilization treatment, the film is stretched 0.95 to 1.05 times while being heated at 200 to 350 ° C., more preferably 200 to 300 ° C., and further preferably 230 to 270 ° C. in an oxidizing atmosphere such as air. To do. Thereby, the PAN-based precursor fiber is converted into a flame-resistant fiber. At this time, the treatment time is 80 to 160 minutes, and the degree of pressurization is, for example, more than 1.3 g / cm 3 . The basic skeleton of the flameproof fiber is shown in FIG. Thereafter, as an optional step, the obtained flame-resistant fibers are activated while being heated in an oxidizing atmosphere such as air, preferably at 800 to 1200 ° C., to obtain activated carbon fibers.
　続いて、得られた活性炭素繊維（または耐炎化繊維）を炭素化処理する。窒素等の不活性雰囲気中、最高温度として、好ましくは６００～９００℃、より好ましくは７００～８００℃で加熱しつつ、１．０～１．１倍に延伸する。次に、窒素等の不活性雰囲気中、最高温度として、好ましくは１０００～１８００℃、より好ましくは１２００～１５００℃で加熱しつつ、０．９５～１．０倍に延伸することにより炭素化繊維が得られる。なお、前記耐炎化繊維の基本骨格は図３６の（ｃ）に示している。図３６の（ｃ）に示すように、炭素化繊維は、「炭素－炭素」結合の途中に窒素原子が存在するため、その導電性は、黒鉛化処理後の黒鉛化繊維と比較して、低い。 Subsequently, the activated carbon fiber (or flame resistant fiber) obtained is carbonized. In an inert atmosphere such as nitrogen, the film is stretched 1.0 to 1.1 times while heating at a maximum temperature of preferably 600 to 900 ° C, more preferably 700 to 800 ° C. Next, the carbonized fiber is stretched 0.95 to 1.0 times while heating at a maximum temperature of preferably 1000 to 1800 ° C., more preferably 1200 to 1500 ° C. in an inert atmosphere such as nitrogen. Is obtained. The basic skeleton of the flameproof fiber is shown in FIG. As shown in FIG. 36 (c), the carbonized fiber has a nitrogen atom in the middle of the “carbon-carbon” bond, so its conductivity is higher than that of the graphitized fiber after graphitization. Low.
　本実施形態におけるＰＡＮ系炭素繊維の製造方法では行わないが、一般的なＰＡＮ系炭素繊維の製造方法では必須に行われる黒鉛化処理について、念のため説明する。前記炭素化繊維を、窒素等の不活性雰囲気中、最高温度として、好ましくは２０００～３０００℃、より好ましくは２２００～３０００℃、さらに好ましくは２２００～２８００℃で加熱しつつ、１．０１～１．２倍に延伸する。その際、処理時間は、例えば１５０～４００秒である。なお、前記黒鉛化繊維の基本骨格は図３６の（ｄ）に示している。このようにして得られた黒鉛化繊維に対して、表面酸化処理、好ましくは酸又はアルカリ水溶液中で１０～２００クーロン／ｇの電解酸化処理を行い、繊維表面に接着性を高める官能基を生じさせる場合がある。 Although not performed in the method for producing a PAN-based carbon fiber in the present embodiment, a graphitization treatment which is essential in a general method for producing a PAN-based carbon fiber will be described just in case. While the carbonized fiber is heated at a maximum temperature of 2000 to 3000 ° C., more preferably 2200 to 3000 ° C., and further preferably 2200 to 2800 ° C. in an inert atmosphere such as nitrogen, 1.01 to 1 2. Stretch 2 times. At this time, the processing time is, for example, 150 to 400 seconds. The basic skeleton of the graphitized fiber is shown in FIG. The graphitized fiber thus obtained is subjected to a surface oxidation treatment, preferably an electrolytic oxidation treatment of 10 to 200 coulomb / g in an acid or alkaline aqueous solution, to produce a functional group that enhances adhesion on the fiber surface. There is a case to let you.
　本実施形態では、上述したように、炭素化処理後、そのまま表面処理やサイジングからなる仕上げ処理（フィラメントの切断）を行う。この処理により得られたチョップドファイバを、紙を作るのと同様に抄紙化する。抄紙化の方法や条件については従来公知のものを適用すれば良い。用いる材料としては、多孔質材料層の構成成分（炭素繊維など）、活性炭、パルプ（セルロース繊維など）、人造黒鉛微粉などが挙げられる。各材料の添加割合は抄紙化可能な範囲であれば、特に制限されない。得られる抄紙の寸法、重さについても特に制限されない。続いて行う抄紙焼成の条件としては、抄紙に含まれる材料の黒鉛化が実現できる最適な温度及び時間で実施する限り、特に限定されない。一例として、１０００～２５００℃で１～４８時間とすることができる。 In this embodiment, as described above, after the carbonization treatment, the finishing treatment (filament cutting) including surface treatment and sizing is performed as it is. The chopped fiber obtained by this treatment is made into paper as in the case of making paper. A conventionally known method may be applied to the papermaking method and conditions. Examples of the material to be used include components of the porous material layer (such as carbon fiber), activated carbon, pulp (such as cellulose fiber), and artificial graphite fine powder. The addition ratio of each material is not particularly limited as long as it can be made into paper. There are no particular restrictions on the size and weight of the paper to be obtained. The conditions for the subsequent papermaking firing are not particularly limited as long as the conditions are set at an optimal temperature and time that can realize graphitization of the material contained in the papermaking. As an example, the temperature may be 1000 to 2500 ° C. for 1 to 48 hours.
　ここで、抄紙化する際、好ましくはファイバの表面を従来公知のフッ素系液体を用いて撥水処理加工を行う。抄紙化されたシートは、厚みが０．２～２ｍｍ／枚で、かつ１００～２５０ｇ／ｍ２の密度を有することが好ましい。このシートを１～５枚積層して、窒素やアルゴンなどの不活性ガス雰囲気中で焼成する。焼成は上記シートの反りを防止するため、例えば黒鉛板の間に挟んで行っても良い。焼成の昇温は、約８００℃以下（最高到達温度）で５～１００時間行うのが好ましい。焼成の最終温度は特に制限されない。これにより、ガス拡散層のロール状シートを得ることができる。 Here, when making the paper, the surface of the fiber is preferably subjected to a water-repellent treatment using a conventionally known fluorine-based liquid. The paper-made sheet preferably has a thickness of 0.2 to 2 mm / sheet and a density of 100 to 250 g / m 2 . 1 to 5 sheets are laminated and fired in an inert gas atmosphere such as nitrogen or argon. Firing may be performed, for example, between graphite plates in order to prevent warpage of the sheet. The firing temperature is preferably raised to about 800 ° C. or lower (maximum temperature reached) for 5 to 100 hours. The final temperature for firing is not particularly limited. Thereby, the roll-shaped sheet of a gas diffusion layer can be obtained.
　ここで、前記撥水処理加工についてより詳細に説明する。ガス拡散層に対しては、撥水性をより高めてフラッディング現象などを防止することを目的として、撥水剤を用いることが好ましい。撥水剤としては、特に限定されないが、ポリテトラフルオロエチレン（ＰＴＦＥ）、ポリフッ化ビニリデン（ＰＶｄＦ）、ポリヘキサフルオロプロピレン、テトラフルオロエチレン－ヘキサフルオロプロピレン共重合体（ＦＥＰ）などのフッ素系の高分子材料、ポリプロピレン、ポリエチレンなどが挙げられる。 Here, the water repellent treatment will be described in more detail. For the gas diffusion layer, it is preferable to use a water repellent for the purpose of further improving the water repellency and preventing the flooding phenomenon. The water repellent is not particularly limited, but fluorine-based high repellents such as polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), polyhexafluoropropylene, and tetrafluoroethylene-hexafluoropropylene copolymer (FEP). Examples thereof include molecular materials, polypropylene, and polyethylene.
　また、撥水性をより向上させるために、ガス拡散層は、撥水剤を含むカーボン粒子の集合体からなるカーボン粒子層（マイクロポーラス層）を基材の触媒層側に有するものであっても良い。 In order to further improve the water repellency, the gas diffusion layer may have a carbon particle layer (microporous layer) made of an aggregate of carbon particles containing a water repellent on the catalyst layer side of the substrate. good.
　カーボン粒子層に含まれるカーボン粒子は特に限定されず、カーボンブラック、グラファイト、膨張黒鉛などが適宜採用される。なかでも、電子伝導性に優れ、比表面積が大きいことから、オイルファーネスブラック、チャネルブラック、ランプブラック、サーマルブラック、アセチレンブラックなどのカーボンブラックが好ましく用いられる。カーボン粒子の平均粒子径は、１０ｎｍ～１００ｎｍ程度とするのが良い。これにより、毛細管力による高い排水性が得られるとともに、触媒層との接触性も向上させることができる。 The carbon particles contained in the carbon particle layer are not particularly limited, and carbon black, graphite, expanded graphite and the like are appropriately employed. Of these, carbon blacks such as oil furnace black, channel black, lamp black, thermal black, and acetylene black are preferably used because of excellent electron conductivity and a large specific surface area. The average particle diameter of the carbon particles is preferably about 10 nm to 100 nm. Thereby, while being able to obtain the high drainage property by capillary force, the contact property with a catalyst layer can also be improved.
　カーボン粒子層に用いられる撥水剤としては、上述した撥水剤と同様のものが挙げられる。なかでも、撥水性、電極反応時の耐食性などに優れることから、フッ素系の高分子材料が好ましく用いられる。 Examples of the water repellent used for the carbon particle layer include the same water repellents as described above. Of these, fluorine-based polymer materials are preferably used because of their excellent water repellency and corrosion resistance during electrode reaction.
　カーボン粒子層におけるカーボン粒子と撥水剤との混合比は、撥水性及び電子伝導性のバランスを考慮して、質量比で９０：１０～４０：６０（カーボン粒子：撥水剤）程度とするのが良い。なお、カーボン粒子層の厚さについても特に制限はなく、得られるガス拡散層の撥水性を考慮して適宜決定すれば良い。 The mixing ratio of the carbon particles to the water repellent in the carbon particle layer is about 90:10 to 40:60 (carbon particles: water repellent) in mass ratio in consideration of the balance between water repellency and electron conductivity. Is good. In addition, there is no restriction | limiting in particular also about the thickness of a carbon particle layer, What is necessary is just to determine suitably considering the water repellency of the gas diffusion layer obtained.
　なかでも、本実施形態における燃料電池用ガス拡散層は、ＰＥＦＣ以外にも、ＰＡＦＣ、ＭＣＦＣ、ＳＯＦＣ又はＡＦＣなどの各種の燃料電池用ガス拡散層としても好適に使用可能である。これらの燃料電池に共通して、導電性の向上や大幅なコストダウンを図ることができる。そして、本実施形態の導電部材に用いることができるセパレータとしては、第一～第三実施形態のセパレータを用いることが好ましいが、それ以外の公知のセパレータも用いることができる。 Especially, the gas diffusion layer for fuel cells in this embodiment can be suitably used as various gas diffusion layers for fuel cells such as PAFC, MCFC, SOFC or AFC in addition to PEFC. In common with these fuel cells, the conductivity can be improved and the cost can be greatly reduced. As the separator that can be used for the conductive member of this embodiment, the separators of the first to third embodiments are preferably used, but other known separators can also be used.
　以下、本実施形態の導電部材（ガス拡散層）の効果を、実施例及び比較例を用いて説明するが、本発明の技術的範囲はこれらの実施例に限定されない。 Hereinafter, the effects of the conductive member (gas diffusion layer) of the present embodiment will be described using Examples and Comparative Examples, but the technical scope of the present invention is not limited to these Examples.
　［実施例IV－１］
　まず、炭素化ＧＤＬを用意した。なお、前記炭素化ＧＤＬとは、炭素化処理まで施されたＰＡＮ系炭素繊維からなる多孔質材料層である。 [Example IV-1]
First, carbonized GDL was prepared. The carbonized GDL is a porous material layer made of PAN-based carbon fiber that has been subjected to carbonization treatment.
　　＜クロム層及び導電性炭素層の積層＞
　まず、ＵＢＭＳスパッタ法により、中間層（Ｃｒ層）の積層を行った。チャンバの真空度を３～１０Ｐａ程度まで排気し、その後、アルゴンガスを１Ｐａ程度導入した。また、多孔質材料層自体の温度を材質を考慮することなく、８０℃とした。 <Lamination of chromium layer and conductive carbon layer>
First, an intermediate layer (Cr layer) was laminated by UBMS sputtering. The degree of vacuum in the chamber was evacuated to about 3 to 10 Pa, and then argon gas was introduced to about 1 Pa. The temperature of the porous material layer itself was set to 80 ° C. without considering the material.
　ＵＢＭＳスパッタリングの際、多孔質材料層の材質を考慮することなく、ガス拡散層に対して１４０Ｖのバイアス電圧をかけた。ターゲットとして９９％以上のＣｒを用いた。このようにして、厚さ２０ｎｍのＣｒ層を多孔質材料層の表面上に中間層として積層させた。 During the UBMS sputtering, a bias voltage of 140 V was applied to the gas diffusion layer without considering the material of the porous material layer. 99% or more of Cr was used as a target. In this way, a Cr layer having a thickness of 20 nm was laminated as an intermediate layer on the surface of the porous material layer.
　続いて、ＵＢＭＳスパッタ法により、導電性炭素層の積層を行った。ターゲットとして９９％以上の黒鉛を用いた点を除き、中間層の積層と同一の方法・条件で導電性炭素層を積層した。得られた導電性炭素層は、グラフェン面の積層体構造を有していることを確認し、その厚さは７μｍであった。 Subsequently, a conductive carbon layer was laminated by UBMS sputtering. Except for using 99% or more of graphite as a target, a conductive carbon layer was laminated by the same method and conditions as the lamination of the intermediate layer. The obtained conductive carbon layer was confirmed to have a laminated structure with a graphene surface, and its thickness was 7 μm.
　［比較例IV－１］
　比較例として、市販の黒鉛化ＧＤＬであるＴＧＰ－Ｈ－９０（東レ社製）を用いた。 [Comparative Example IV-1]
As a comparative example, commercially available graphitized GDL, TGP-H-90 (manufactured by Toray Industries, Inc.) was used.
　［比較例IV－２］
　炭素化処理まで施されたＰＡＮ系炭素繊維を多孔質材料層のみからなる燃料電池用ＧＤＬを製造した。ちなみに、多孔質材料層は、実施例IV－１と同様のものを使用した。なお、クロム（Ｃｒ）層及び導電性炭素層の積層は行っていない。そのため、得られた燃料電池用ＧＤＬは、グラフェン面の積層体構造を有しない。 [Comparative Example IV-2]
A GDL for a fuel cell was produced, in which a PAN-based carbon fiber that had been subjected to carbonization treatment consisted of only a porous material layer. Incidentally, the same porous material layer as in Example IV-1 was used. Note that the chromium (Cr) layer and the conductive carbon layer are not stacked. Therefore, the obtained GDL for a fuel cell does not have a graphene-surface stacked body structure.
　［Ｒ値の測定］
　上記の実施例及び各比較例において作製したガス拡散層において、導電性炭素層のＲ値の測定を行った。具体的には、まず、顕微ラマン分光器を用いて、導電性炭素層のラマンスペクトルを計測した。そして、１３００～１４００ｃｍ－１に位置するバンド（Ｄバンド）のピーク強度（ＩＤ）と、１５００～１６００ｃｍ－１に位置するバンド（Ｇバンド）のピーク強度（ＩＧ）とのピーク面積比（ＩＤ／ＩＧ）を算出して、Ｒ値とした。得られた結果を下記の表５に示す。 [Measurement of R value]
In the gas diffusion layers produced in the above examples and comparative examples, the R value of the conductive carbon layer was measured. Specifically, first, the Raman spectrum of the conductive carbon layer was measured using a microscopic Raman spectrometer. Then, 1300 ~ 1400 cm peak intensity of the bands (D-band) located -1 (I D), the peak area ratio of the peak intensity (I G) of band (G-band) located 1500 ~ 1600 cm -1 ( I D / I G ) was calculated and used as the R value. The results obtained are shown in Table 5 below.
　［接触抵抗の測定］
　上記の実施例及び各比較例で得られたガス拡散層とセパレータとの接触抵抗の測定を行った。図３９は、実施例及び各比較例で得られた燃料電池用ガス拡散層とセパレータとの接触抵抗の計測方法を示す図である。図３９に示すように、セパレータ３６０として、ガス拡散層３６２側の表面に金メッキを施したステンレスプレートを用いた。そして、作製したガス拡散層３６２を１対のセパレータ３６０で挟持し、その両端に電源を接続し、セパレータ３６０の各主表面に対して垂直方向から１ＭＰａの荷重をかけつつ保持し、測定装置を構成した。この測定装置の両端に１Ａの定電流を流し、その際の電圧値及びオームの法則より、積層体の接触抵抗値を算出した。得られた結果を下記の表５に示す。 [Measurement of contact resistance]
The contact resistance between the gas diffusion layer and the separator obtained in the above examples and comparative examples was measured. FIG. 39 is a diagram showing a method for measuring the contact resistance between the gas diffusion layer for a fuel cell and the separator obtained in the examples and the comparative examples. As shown in FIG. 39, as the separator 360, a stainless steel plate having a gold-plated surface on the gas diffusion layer 362 side was used. The produced gas diffusion layer 362 is sandwiched between a pair of separators 360, power is connected to both ends of the gas diffusion layer 362, and the measuring device is held while applying a 1 MPa load from the vertical direction to each main surface of the separator 360. Configured. A constant current of 1 A was passed through both ends of this measuring apparatus, and the contact resistance value of the laminate was calculated from the voltage value and Ohm's law at that time. The results obtained are shown in Table 5 below.
　表５に示すように、実施例IV－１と比較例IV－１とで、接触抵抗の値がほぼ同等である。そのため、本実施形態によれば、従来の燃料電池用ガス拡散層と比較して、同等の導電性を確保しつつ、有意にコストダウンを図ることができることを確認した。 As shown in Table 5, the contact resistance values of Example IV-1 and Comparative Example IV-1 are almost the same. Therefore, according to the present embodiment, it has been confirmed that the cost can be significantly reduced while ensuring the same conductivity as compared with the conventional gas diffusion layer for fuel cells.
Figure JPOXMLDOC01-appb-T000006
Figure JPOXMLDOC01-appb-T000006
　また、表５に示す実施例IV－１の接触抵抗に関する結果に対応するグラフを図４０に示す。当該グラフは、ＰＡＮ系炭素化繊維に対する「導電性の炭素」の重量比（導電性の炭素／ＰＡＮ系炭素化繊維）を横軸にとった時の、接触抵抗の値を示している。すなわち、図４０は、導電性炭素層の増加と接触抵抗との関係を示す。図４０に示すように、本実施形態におけるＰＡＮ系炭素化繊維自体は、導電性の面で、黒鉛化処理まで施したＰＡＮ系炭素繊維より劣る。しかし、このようなＰＡＮ系炭素化繊維で構成される多孔質材料層において、導電性炭素層の積層量に比例して接触抵抗が低下する。言い換えれば、本実施形態に係るガス拡散層は、導電性の観点で、黒鉛化処理したＰＡＮ系炭素繊維からなるガス拡散層と同等となる。その上で、本実施形態に係るＰＡＮ系炭素化繊維は、通常のＰＡＮ系炭素繊維と異なり、黒鉛化処理を行わないため、大幅なコストダウンを図ることができる。 Further, a graph corresponding to the results regarding the contact resistance of Example IV-1 shown in Table 5 is shown in FIG. The graph shows the value of contact resistance when the horizontal axis represents the weight ratio of “conductive carbon” to PAN-based carbonized fiber (conductive carbon / PAN-based carbonized fiber). That is, FIG. 40 shows the relationship between the increase in the conductive carbon layer and the contact resistance. As shown in FIG. 40, the PAN-based carbonized fiber itself in this embodiment is inferior to the PAN-based carbon fiber subjected to the graphitization treatment in terms of conductivity. However, in the porous material layer composed of such PAN-based carbonized fibers, the contact resistance decreases in proportion to the amount of the conductive carbon layer laminated. In other words, the gas diffusion layer according to this embodiment is equivalent to a gas diffusion layer made of graphitized PAN-based carbon fiber from the viewpoint of conductivity. In addition, unlike the normal PAN-based carbon fiber, the PAN-based carbonized fiber according to the present embodiment does not perform graphitization, and thus can greatly reduce the cost.
　なお、上記炭素繊維及び導電性の炭素は共に、オージェ電子分光法では炭素（Ｃ）として検出される。したがって、両者を区別することはできない。そのため、導電性炭素層を成膜する前の中間層を成膜した時点で、中間層の構成元素の上には必ず導電性炭素層が成膜されるという前提で、炭素繊維及び中間層の構成金属に対してＡＥＳの面マッピングを行った。このような過程を経て、上記炭素繊維に対する「導電性の炭素」の比を算出した。 Note that both the carbon fiber and the conductive carbon are detected as carbon (C) by Auger electron spectroscopy. Therefore, the two cannot be distinguished. Therefore, when the intermediate layer before forming the conductive carbon layer is formed, it is assumed that the conductive carbon layer is always formed on the constituent elements of the intermediate layer. AES surface mapping was performed on the constituent metals. Through such a process, the ratio of “conductive carbon” to the carbon fiber was calculated.
　［参考例IV－１］
　導電性炭素層上に金からなる親水化層を積層した場合の、導電性の炭素に対するＡｕの比（Ａｕ／導電性の炭素）、並びに接触角を求めた。 [Reference Example IV-1]
The ratio of Au to conductive carbon (Au / conductive carbon) and the contact angle when a hydrophilic layer made of gold was laminated on the conductive carbon layer were determined.
　上記実施例IV－１で得られたガス拡散層に対して、チャンバの真空度を３～１０Ｐａ程度まで排気し、その後、アルゴンガスを１Ｐａ程度導入した。また、ガス拡散層自体の温度を材質を考慮することなく、８０℃とした。 The chamber was evacuated to about 3 to 10 Pa with respect to the gas diffusion layer obtained in Example IV-1, and then about 1 Pa of argon gas was introduced. The temperature of the gas diffusion layer itself was set to 80 ° C. without considering the material.
　ＵＢＭＳスパッタリングの際、多孔質材料層の材質を考慮することなく、ガス拡散層に対して１４０Ｖのバイアス電圧をかけた。そして、ターゲットとして９９％以上のＡｕを用いた。このようにして、厚さ５ｎｍのＡｕ層（親水化層）を導電性炭素層の表面に積層した。 During the UBMS sputtering, a bias voltage of 140 V was applied to the gas diffusion layer without considering the material of the porous material layer. And 99% or more of Au was used as a target. In this way, an Au layer (hydrophilic layer) having a thickness of 5 nm was laminated on the surface of the conductive carbon layer.
　Ａｕの配置は、多孔質材料層が多孔質性であるため、オージェ電子分光法の面マッピング及び画像解析によって算出した。そして、導電性の炭素及びＡｕの面積比（Ａｕ面積／導電性炭素面積）に対する水の静的接触角を測定した。ここで、接触角の測定は、ＪＩＳ　Ｋ６７６８に準拠して行った。より具体的には、２４℃及び湿度（ＲＨ）４９％の条件下、純水（６μＬ）を用いて静的な接触角を測定した。測定装置として、協和界面科学（株）製のＤＭ７００（θ／２法）を用いた。測定結果のグラフを図４１に示す。 The arrangement of Au was calculated by surface mapping and image analysis of Auger electron spectroscopy because the porous material layer is porous. And the static contact angle of water with respect to the area ratio (Au area / conductive carbon area) of conductive carbon and Au was measured. Here, the contact angle was measured according to JIS K6768. More specifically, the static contact angle was measured using pure water (6 μL) under the conditions of 24 ° C. and humidity (RH) 49%. As a measuring device, DM700 (θ / 2 method) manufactured by Kyowa Interface Science Co., Ltd. was used. A graph of the measurement results is shown in FIG.
　Ａｕの存在しない状態（ネガティブ・コントロール）では、公知の炭素の接触角は８５度付近を示した。これに対し、Ａｕの配置される量に比例して親水性が増大することを確認した。 In the absence of Au (negative control), the known carbon contact angle was around 85 degrees. In contrast, it was confirmed that the hydrophilicity increased in proportion to the amount of Au arranged.
　［参考例IV－２］
　導電性炭素層の表面にＡｕを分散させつつスパッタした場合の抵抗低減効果を調べた。 [Reference Example IV-2]
The resistance reduction effect when sputtering while dispersing Au on the surface of the conductive carbon layer was investigated.
　上記実施例IV－１で得られたガス拡散層に対して、チャンバの真空度を３～１０Ｐａ程度まで排気し、その後、アルゴンガスを５Ｐａ程度導入した。また、ガス拡散層自体の温度を材質を考慮することなく、８０℃とした。 The vacuum degree of the chamber was evacuated to about 3 to 10 Pa with respect to the gas diffusion layer obtained in Example IV-1, and then about 5 Pa of argon gas was introduced. The temperature of the gas diffusion layer itself was set to 80 ° C. without considering the material.
　ＵＢＭＳスパッタリングの際、多孔質材料層の材質を考慮することなく、ガス拡散層に対して１４０Ｖのバイアス電圧をかけた。そして、ターゲットとして９９％以上のＡｕを用いた。その際、Ａｕが導電性炭素層の表面にスパッタされるのと同時並行で、当該ガス拡散層の接触抵抗を測定した。結果のグラフを図４２に示す。 During the UBMS sputtering, a bias voltage of 140 V was applied to the gas diffusion layer without considering the material of the porous material layer. And 99% or more of Au was used as a target. At that time, the contact resistance of the gas diffusion layer was measured in parallel with Au being sputtered on the surface of the conductive carbon layer. The resulting graph is shown in FIG.
　実施例IV－１のように、ガス拡散層において、導電性炭素層を配置することによっても十分に小さな接触抵抗を確保できる。しかし、図４２に示すように、さらにＡｕを配置することによって、接触抵抗をさらに低減させることができることを確認した。その上、ガス拡散層における親水化層の存在によって、触媒層からセパレータ側への水の排出を迅速に行うことも可能となる。前記親水化層が金属酸化物で構成される場合、このような親水化が得られる。一方で、前記親水化層が非金属酸化物（Ａｕ等）で構成される場合、前記の親水化に加えて、導電性にも極めて優れるため、接触抵抗の低減効果も得られる。 As in Example IV-1, a sufficiently small contact resistance can be secured by disposing a conductive carbon layer in the gas diffusion layer. However, as shown in FIG. 42, it was confirmed that the contact resistance can be further reduced by further arranging Au. In addition, the presence of the hydrophilic layer in the gas diffusion layer makes it possible to quickly discharge water from the catalyst layer to the separator side. When the hydrophilic layer is made of a metal oxide, such hydrophilicity can be obtained. On the other hand, when the hydrophilic layer is composed of a non-metal oxide (Au or the like), in addition to the hydrophilic property, the conductivity is extremely excellent, so that an effect of reducing contact resistance can be obtained.
［第五実施形態］
　次に、本発明の第五実施形態に係る導電部材及びその製造方法について、図面に基づき詳細に説明する。なお、第一実施形態と同一構成には同一符号を付し、重複する説明は省略する。 [Fifth embodiment]
Next, the conductive member and the manufacturing method thereof according to the fifth embodiment of the present invention will be described in detail with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same structure as 1st embodiment, and the overlapping description is abbreviate | omitted.
　本実施形態に係る導電部材は、金属基材、中間層及び導電性炭素層が積層されてなる燃料電池用セパレータ（導電積層体）と、複数の空孔を有するガス拡散基体を含むガス拡散層と、を備えている。そして、前記導電性炭素層と前記ガス拡散層とが対向するように積層されている。さらに、導電性炭素層の表面であってガス拡散層と接触する領域に親水導電性粒子が分散されている。また、導電性粒子の粒子径及び導電性粒子間の距離が前記ガス拡散基体の空孔間距離以下である。 The conductive member according to the present embodiment includes a fuel cell separator (conductive laminate) in which a metal substrate, an intermediate layer, and a conductive carbon layer are laminated, and a gas diffusion layer including a gas diffusion substrate having a plurality of pores. And. The conductive carbon layer and the gas diffusion layer are stacked so as to face each other. Furthermore, hydrophilic conductive particles are dispersed in a region on the surface of the conductive carbon layer and in contact with the gas diffusion layer. Further, the particle diameter of the conductive particles and the distance between the conductive particles are not more than the distance between the holes of the gas diffusion substrate.
　本実施形態に係る固体高分子形燃料電池（ＰＥＦＣ）も第一実施形態に係るＰＥＦＣと同様の基本構成を有する。具体的には、図１に示すように、ＰＥＦＣは、固体高分子電解質膜２と、これを挟持する一対の触媒層（アノード触媒層３ａ及びカソード触媒層３ｂ）とを有する。そして、固体高分子電解質膜２と触媒層（３ａ、３ｂ）との積層体はさらに、一対のガス拡散層（アノードガス拡散層４ａ及びカソードガス拡散層４ｂ）により挟持されている。このように、固体高分子電解質膜２、一対の触媒層（３ａ、３ｂ）及び一対のガス拡散層（４ａ、４ｂ）は、積層された状態で膜電極接合体９を構成する。 The polymer electrolyte fuel cell (PEFC) according to this embodiment also has the same basic configuration as the PEFC according to the first embodiment. Specifically, as shown in FIG. 1, the PEFC has a solid polymer electrolyte membrane 2 and a pair of catalyst layers (an anode catalyst layer 3a and a cathode catalyst layer 3b) that sandwich the membrane. The laminate of the solid polymer electrolyte membrane 2 and the catalyst layers (3a, 3b) is further sandwiched between a pair of gas diffusion layers (anode gas diffusion layer 4a and cathode gas diffusion layer 4b). Thus, the solid polymer electrolyte membrane 2, the pair of catalyst layers (3a, 3b), and the pair of gas diffusion layers (4a, 4b) constitute the membrane electrode assembly 9 in a stacked state.
　ＰＥＦＣ１において、ＭＥＡ９はさらに、一対のセパレータ（アノードセパレータ５ａ及びカソードセパレータ５ｂ）により挟持されている。すなわち、セパレータ（５ａ、５ｂ）はガス拡散層（４ａ、４ｂ）と隣接して配置され、隣り合うセパレータ（５ａ、５ｂ）及びガス拡散層（４ａ、４ｂ）は導電部材（８ａ、８ｂ）を構成する。 In PEFC1, the MEA 9 is further sandwiched between a pair of separators (anode separator 5a and cathode separator 5b). That is, the separators (5a, 5b) are disposed adjacent to the gas diffusion layers (4a, 4b), and the adjacent separators (5a, 5b) and the gas diffusion layers (4a, 4b) include the conductive members (8a, 8b). Constitute.
　図４３は、本実施形態に係る導電部材４０８の概略構成を示す断面図である。本実施形態において、導電部材４０８は、ガス拡散層４０４及びセパレータ４０５から構成される。セパレータ４０５は、金属基材４５２と、導電性炭素層４５４とを有する。そして、導電性炭素層４５４の表面であって前記ガス拡散層４０４と接触する領域４０９に親水導電性粒子４５７が分散されている。また、金属基材４５２と、導電性炭素層４５４との間には、中間層４５６が介在している。なお、ＰＥＦＣにおいて、セパレータ４０５は、導電性炭素層４５４がＭＥＡ９側に位置するように、配置される。以下、本実施形態の導電部材４０８の各構成要素について詳述する。 FIG. 43 is a cross-sectional view showing a schematic configuration of the conductive member 408 according to the present embodiment. In the present embodiment, the conductive member 408 includes a gas diffusion layer 404 and a separator 405. The separator 405 includes a metal substrate 452 and a conductive carbon layer 454. Then, hydrophilic conductive particles 457 are dispersed in a region 409 that is in contact with the gas diffusion layer 404 on the surface of the conductive carbon layer 454. In addition, an intermediate layer 456 is interposed between the metal substrate 452 and the conductive carbon layer 454. In the PEFC, the separator 405 is arranged so that the conductive carbon layer 454 is located on the MEA 9 side. Hereinafter, each component of the conductive member 408 of this embodiment will be described in detail.
　（セパレータ）
　［金属基材］
　金属基材４５２は、セパレータ４０５の主層であり、導電性及び機械的強度の確保に寄与する。そして、金属基材４５２を構成する金属は、第一実施形態における金属基材３１と同様の金属を用いることができる。 (Separator)
[Metal base material]
The metal substrate 452 is a main layer of the separator 405, and contributes to ensuring conductivity and mechanical strength. And the metal which comprises the metal base material 452 can use the metal similar to the metal base material 31 in 1st embodiment.
　［導電性炭素層］
　導電性炭素層４５４は、導電性炭素を含む層である。この層の存在によって、セパレータ４０５の導電性を確保しつつ、金属基材４５２のみの場合と比較して耐食性が改善される。このような導電性炭素層４５４としては、第一実施形態の導電性炭素層３３を使用することができる。 [Conductive carbon layer]
The conductive carbon layer 454 is a layer containing conductive carbon. The presence of this layer improves the corrosion resistance as compared with the case of only the metal substrate 452 while ensuring the conductivity of the separator 405. As such a conductive carbon layer 454, the conductive carbon layer 33 of the first embodiment can be used.
　［親水導電性粒子］
　親水導電性粒子４５７は、親水性を有する導電性粒子である。そして、親水導電性粒子４５７は、導電性炭素層４５４の表面であってガス拡散層４０４と接触する領域４０９に分散されている。この導電性粒子４５７の存在により、導電性炭素層４５４に親水性が付与されると共に、導電性が一層向上し、ガス拡散層４０４との接触抵抗を低下させることができる。なお、導電性粒子は接触領域４０９に加えて、接触領域４０９以外の導電性炭素層の表面や導電性炭素層の内部に存在していても良い。ただし、接触抵抗の低減効果及び親水性向上効果を発揮し、かつ製造コストを低減するために、導電性粒子４５７は導電性炭素層４５４の表層に存在することが好ましい。より具体的には、最低限の厚さで、面内で均一な分散がされているのが好ましい。このため、厚さと分散性とは、製造方法や条件に依存するところが大きい。本実施形態で確認できている導電性炭素層の平均厚さとしては、０．００５μｍ～１μｍで存在することが好ましい。 [Hydrophilic conductive particles]
The hydrophilic conductive particles 457 are conductive particles having hydrophilicity. The hydrophilic conductive particles 457 are dispersed in a region 409 that is in contact with the gas diffusion layer 404 on the surface of the conductive carbon layer 454. By the presence of the conductive particles 457, hydrophilicity is imparted to the conductive carbon layer 454, conductivity is further improved, and contact resistance with the gas diffusion layer 404 can be reduced. In addition to the contact region 409, the conductive particles may be present on the surface of the conductive carbon layer other than the contact region 409 or inside the conductive carbon layer. However, it is preferable that the conductive particles 457 be present on the surface layer of the conductive carbon layer 454 in order to exert a contact resistance reduction effect and a hydrophilicity improvement effect and reduce the manufacturing cost. More specifically, it is preferable that uniform dispersion is performed in a plane with a minimum thickness. For this reason, the thickness and dispersibility largely depend on the manufacturing method and conditions. The average thickness of the conductive carbon layer confirmed in this embodiment is preferably 0.005 μm to 1 μm.
　導電性粒子としては、導電性及び親水性を有する材料であれば、特に制限されない。本実施形態において、導電性炭素層が有する水との静的接触角は８５～１００°であることから、親水性とはこの静的接触角よりも小さいことをいう。なお、親水性とは、好ましくは水との静的接触角が７０°以下、より好ましくは６０°以下であることをいう。導電性粒子としては、具体的には、貴金属、貴金属を含む合金、導電性窒化物、及び導電性酸化物からなる群より選択される少なくとも一種を含むことが好ましい。貴金属としては、金（Ａｕ）、銀（Ａｇ）、白金（Ｐｔ）、パラジウム（Ｐｄ）、ロジウム（Ｒｈ）、イリジウム（Ｉｒ）、ルテニウム（Ｒｕ）、オスミウム（Ｏｓ）よりなる群から選択される少なくとも一種が好ましく挙げられる。貴金属を含む合金としては、金－コバルト合金（Ａｕ－Ｃｏ）、金－ニッケル合金（Ａｕ－Ｎｉ）、パラジウム－ニッケル合金（Ｐｄ－Ｎｉ）などが挙げられる。導電性窒化物としては、ＣｒＮ、ＴｉＮ、ＺｒＮ、ＨｆＮなどが挙げられる。導電性酸化物としては、ＭＢａ２Ｃｕ３Ｏ７－ｘ（ＭはＹ、又はＣｅ、Ｐｒ、Ｔｂを除く希土類元素）、ＳｎＯ２、Ｉｎ２Ｏ３、ＣｒＯ２、Ｆｅ３Ｏ４、ＩｒＯ２、ＯｓＯ２、ＰｔＯ２、ＲｅＯ２（β）、ＲｅＯ３、ＲｈＯ２、ＲｕＯ２、ＷＯ２、Ｗ１８Ｏ４９、Ｖ２Ｏ３、Ｖ７Ｏ１３、Ｖ８Ｏ１５、Ｖ６Ｏ１３よりなる群から選択される少なくとも一種が好ましく挙げられる。これらのなかでも、高い導電性を有する点で、白金（Ｐｔ）、金（Ａｕ）、銀（Ａｇ）、が好ましく、コスト面からは、銀（Ａｇ）、がより好ましい。また、金（Ａｕ）は、リサイクルも含めた利用を考慮すると、コスト面においても好適に用いられる。なお、これらの貴金属、及び貴金属を含む合金、導電性窒化物、ならびに導電性酸化物の種類については、一種単独で用いても良く、二種以上を混合させて用いても良い。 The conductive particle is not particularly limited as long as it is a material having conductivity and hydrophilicity. In the present embodiment, since the static contact angle with water of the conductive carbon layer is 85 to 100 °, the hydrophilic property means smaller than the static contact angle. The hydrophilicity preferably means that the static contact angle with water is 70 ° or less, more preferably 60 ° or less. Specifically, the conductive particles preferably include at least one selected from the group consisting of noble metals, alloys containing noble metals, conductive nitrides, and conductive oxides. The noble metal is selected from the group consisting of gold (Au), silver (Ag), platinum (Pt), palladium (Pd), rhodium (Rh), iridium (Ir), ruthenium (Ru), and osmium (Os). At least one is preferred. Examples of the alloy containing a noble metal include a gold-cobalt alloy (Au—Co), a gold-nickel alloy (Au—Ni), a palladium-nickel alloy (Pd—Ni), and the like. Examples of the conductive nitride include CrN, TiN, ZrN, and HfN. As the conductive oxide, MBa 2 Cu 3 O 7-x (M is Y or a rare earth element other than Ce, Pr, and Tb), SnO 2 , In 2 O 3 , CrO 2 , Fe 3 O 4 , IrO 2 , OsO 2 , PtO 2 , ReO 2 (β), ReO 3 , RhO 2 , RuO 2 , WO 2 , W 18 O 49 , V 2 O 3 , V 7 O 13 , V 8 O 15 , V 6 O 13 Preferably, at least one selected from the group consisting of Among these, platinum (Pt), gold (Au), and silver (Ag) are preferable from the viewpoint of high conductivity, and silver (Ag) is more preferable from the viewpoint of cost. Gold (Au) is also preferably used in terms of cost in consideration of utilization including recycling. In addition, about the kind of these noble metals, the alloy containing a noble metal, a conductive nitride, and a conductive oxide, you may use individually by 1 type, and may mix and use 2 or more types.
　本実施形態において、導電性粒子の粒子径及び導電性粒子間の距離は、ガス拡散基体の空孔間距離以下であることが好ましい。このような場合には、導電性粒子とガス拡散基体との接点を確保することができ、ガス拡散層との接触抵抗が低減される。本実施形態において、「導電性粒子間の距離」は最近接した２つの導電性粒子の中心間の距離を意味するものとする。「空孔間距離」とは最近接した２つの空孔の中心間の距離を意味するものとする。「導電性粒子間の距離」は、例えば、走査型電子顕微鏡や透過型電子顕微鏡などの観察手段を用い、数～数十視野中に観察される導電性粒子間の距離の平均値として算出される値を採用するものとする。また、「空孔間距離」も同様に、走査型電子顕微鏡や透過型電子顕微鏡などの観察手段を用い、ガス拡散基体の断面における数～数十視野中に観察される空孔間距離の平均値として算出される。 In the present embodiment, the particle diameter of the conductive particles and the distance between the conductive particles are preferably not more than the distance between the holes of the gas diffusion substrate. In such a case, a contact point between the conductive particles and the gas diffusion base can be secured, and the contact resistance with the gas diffusion layer is reduced. In the present embodiment, “distance between conductive particles” means the distance between the centers of the two closest conductive particles. The “inter-hole distance” means the distance between the centers of the two closest holes. The “distance between the conductive particles” is calculated as an average value of the distance between the conductive particles observed in several to several tens of fields using an observation means such as a scanning electron microscope or a transmission electron microscope. Shall be adopted. Similarly, the “inter-hole distance” is the average of inter-hole distances observed in several to several tens of fields in the cross section of the gas diffusion substrate using an observation means such as a scanning electron microscope or a transmission electron microscope. Calculated as a value.
　具体的には、ガス拡散基体が繊維から構成される場合（繊維集合体）には、空孔間距離は繊維の直径に相当する。例えば、図４４Ａに示すように、ガス拡散基体が炭素繊維４５８から構成される場合には、導電性粒子４５７の粒子径及び前記導電性粒子４５７間の距離が前記炭素繊維４５８の直径以下であることが好ましい。また、ガス拡散基体が粒子から構成される場合（粒子集合体）には、空孔間距離は粒子の直径に相当する。例えば、図４４Ａに示すように、ガス拡散基体がカーボン粒子４５８から構成される場合には、導電性粒子４５７の粒子径及び前記導電性粒子４５７間の距離が前記カーボン粒子４５８の直径以下であることが好ましい。このようにガス拡散基体が繊維や粒子から構成される場合には、導電性粒子と炭素繊維又は炭素粒子との接点を確実に確保することができる。 Specifically, when the gas diffusion base is composed of fibers (fiber assembly), the distance between the holes corresponds to the fiber diameter. For example, as shown in FIG. 44A, when the gas diffusion base is composed of carbon fibers 458, the particle diameter of the conductive particles 457 and the distance between the conductive particles 457 are not more than the diameter of the carbon fibers 458. It is preferable. Further, when the gas diffusion substrate is composed of particles (particle aggregate), the distance between the holes corresponds to the diameter of the particles. For example, as shown in FIG. 44A, when the gas diffusion base is composed of carbon particles 458, the particle diameter of the conductive particles 457 and the distance between the conductive particles 457 are not more than the diameter of the carbon particles 458. It is preferable. As described above, when the gas diffusion base is composed of fibers or particles, a contact point between the conductive particles and the carbon fibers or the carbon particles can be reliably ensured.
　ガス拡散基体が金網、貫通孔を有する打ち抜きのプレス板などの多孔性金属から構成される場合には、空孔中心間の最短距離に相当する。例えば、図４４Ｂに示すように、ガス拡散基体が貫通孔４６１を有する多孔性金属４６０から構成される場合には、導電性粒子４５７の粒子径及び前記導電性粒子４５７間の距離が前記多孔性金属４６０の空孔間距離以下であることが好ましい。かかる場合には、多孔性金属中の空孔間距離内にある基材金属の幅よりも小さい間隔で微粒子が存在するため、多数の接点を確保できる。一例を挙げると、導電性粒子の粒子径及び導電性粒子間の距離は１ｎｍ～７μｍである。 When the gas diffusion substrate is made of a porous metal such as a wire mesh or a punched press plate having a through hole, this corresponds to the shortest distance between the hole centers. For example, as shown in FIG. 44B, when the gas diffusion substrate is composed of a porous metal 460 having a through-hole 461, the particle diameter of the conductive particles 457 and the distance between the conductive particles 457 are determined as the porous material 457. The distance between the holes of the metal 460 is preferably equal to or less than the distance. In such a case, since the fine particles exist at intervals smaller than the width of the base metal within the distance between the holes in the porous metal, a large number of contacts can be secured. As an example, the particle diameter of the conductive particles and the distance between the conductive particles are 1 nm to 7 μm.
　導電性粒子による接触領域の被覆率は、１％以上であることが好ましい。１％以上であれば、導電性粒子による親水性及び導電性の向上効果が得られる。より好ましくは２～１００％、さらに好ましくは３～１００％であり、特に好ましくは１０～１００％である。かかる下限値以上であれば、親水性及び導電性が顕著に向上する。一方、上限値は、親水性及び導電性の向上の観点からは大きいほど好ましく、１００％（完全被覆）であることが好ましいが、コスト面を考慮すると、親水性及び導電性が確保される限り被覆率が小さいほうが好ましい。 The coverage of the contact area with conductive particles is preferably 1% or more. If it is 1% or more, the hydrophilicity and electroconductivity improvement effect by electroconductive particle will be acquired. More preferably, it is 2 to 100%, still more preferably 3 to 100%, and particularly preferably 10 to 100%. If it is more than this lower limit, hydrophilicity and electroconductivity will improve notably. On the other hand, the upper limit is preferably as large as possible from the viewpoint of improving hydrophilicity and conductivity, and is preferably 100% (complete coverage). However, in consideration of cost, as long as hydrophilicity and conductivity are ensured. A smaller coverage is preferred.
　ここで、２つの要素間の接触抵抗は、接点を構成する２つの部材の体積固有抵抗（ρ１、ρ２）と接点の半径の逆数（１／ａｎ）の総和から算出される。 Here, the contact resistance between the two elements is calculated from the sum of the volume resistivity (ρ 1 , ρ 2 ) of the two members constituting the contact and the reciprocal of the contact radius (1 / a n ).
Figure JPOXMLDOC01-appb-M000007
Figure JPOXMLDOC01-appb-M000007
（式中、Ｒ：接触抵抗［Ω］、ρ１、ρ２：体積固有抵抗［Ω・ｃｍ］、ａｎ：接点の半径［ｃｍ］、ｎ：接点数）
　ρ１、ρ２は材料固有の値であり、例えば、導電性粒子として金（Ａｕ）を用い、ガス拡散基体として炭素繊維を用いる場合には、ρ１及びρ２はそれぞれ金（Ａｕ）及び炭素繊維の体積固有抵抗となる。したがって、接触抵抗は接点数及び接点の半径に依存することがわかる。 (Wherein, R: contact resistance [Ω], ρ 1, ρ 2: volume resistivity [Ω · cm], a n : radius of the contact [cm], n: number of contact points)
ρ 1 and ρ 2 are values specific to the material. For example, when gold (Au) is used as the conductive particles and carbon fiber is used as the gas diffusion base, ρ 1 and ρ 2 are gold (Au) and This is the volume resistivity of the carbon fiber. Therefore, it can be seen that the contact resistance depends on the number of contacts and the radius of the contacts.
　導電性粒子の被覆率が大きいほど、導電性炭素層の表面に分散される導電性粒子の数が増加する。そのため、導電性粒子とガス拡散基体の接点を増大させることができ、この結果、接触抵抗を低減することができる。 The larger the coverage of the conductive particles, the more conductive particles dispersed on the surface of the conductive carbon layer. Therefore, the contact point between the conductive particles and the gas diffusion base can be increased, and as a result, the contact resistance can be reduced.
　本発明者らは、導電性粒子の被覆率が上記の下限値以上である場合には、ガス拡散基体との接点を有意に増大させることができ、接触抵抗を低減することができることを見出した。そして、本実施形態では、上記で例示した貴金属、貴金属を含む合金、導電性窒化物、及び導電性酸化物などの導電性粒子を用いた場合に、導電性粒子による被覆率が上記の下限値以上であれば、接触抵抗の低減されることが認められた。ただし、ガス拡散基体と導電性粒子との接点は、導電性粒子及びガス拡散基体の材質・サイズ、導電性炭素層の接触領域の表面粗さ・材質に依存する。例えば、接触領域の表面粗さが小さい場合には、接触領域に分散された導電性粒子とガス拡散基体との接点を増大させることができるため、接触抵抗を低減することができる。一方、一般に親水性表面では表面粗さが大きいほど親水性が高いことが知られており、高被覆率の親水化された表面においては、表面粗さが大きい方がより一層の親水化効果を発揮する。このため、好ましくは、使用する導電性粒子、ガス拡散基体、導電性炭素層（接触領域）にあわせて導電性粒子の被覆率を適宜調整するのが良い。 The present inventors have found that when the coverage of the conductive particles is not less than the above lower limit, the contact with the gas diffusion substrate can be significantly increased and the contact resistance can be reduced. . In the present embodiment, when conductive particles such as the noble metal exemplified above, an alloy containing a noble metal, a conductive nitride, and a conductive oxide are used, the coverage by the conductive particles is the above lower limit value. If it was above, it was recognized that contact resistance is reduced. However, the contact point between the gas diffusion substrate and the conductive particles depends on the material and size of the conductive particles and the gas diffusion substrate, and the surface roughness and material of the contact region of the conductive carbon layer. For example, when the surface roughness of the contact region is small, the contact point between the conductive particles dispersed in the contact region and the gas diffusion base can be increased, so that the contact resistance can be reduced. On the other hand, it is generally known that the hydrophilic surface has a higher hydrophilicity as the surface roughness is larger. On the hydrophilic surface with a high coverage, the larger the surface roughness, the more the hydrophilic effect. Demonstrate. For this reason, it is preferable to appropriately adjust the coverage of the conductive particles in accordance with the conductive particles, gas diffusion base, and conductive carbon layer (contact region) to be used.
　また、導電性粒子が分散された接触領域における水の接触角は、７０°以下であることが好ましく、０～６０°であることがより好ましく、４５～５０°であることがさらに好ましい。このような場合は、水の流路となるセパレータ表面の排水性が一層向上される。そのため、特に水の排出性が問題となるリブピッチが小さい（微細な凹凸形状を有する）セパレータにおける細い流路であっても、効率よく排水することができる。なお、本実施形態において接触角は、ＪＩＳ　Ｋ６７６８に記載された濡れ性試験方法に基づいて測定するものとする。 In addition, the contact angle of water in the contact region in which the conductive particles are dispersed is preferably 70 ° or less, more preferably 0 to 60 °, and further preferably 45 to 50 °. In such a case, the drainage performance of the separator surface that becomes the water flow path is further improved. Therefore, even if it is a narrow flow path in a separator with a small rib pitch (having a fine uneven shape) in which water discharge is a problem, water can be efficiently drained. In the present embodiment, the contact angle is measured based on the wettability test method described in JIS K6768.
　なお、導電性粒子は、金属基材の少なくとも一方に形成された導電性炭素層の表面上に存在すれば良い。ただし、導電性炭素層が金属基材の両方の主表面に存在する場合には、両方の導電性炭素層の表面上に導電性粒子が分散されていても良い。ただ、排水性の効果を発揮する上で、導電性粒子は、ＭＥＡ側（反応面側）に配置されることとなる導電性炭素層の表面に存在することが好ましい。 In addition, the electroconductive particle should just exist on the surface of the electroconductive carbon layer formed in at least one side of the metal base material. However, when conductive carbon layers are present on both main surfaces of the metal substrate, conductive particles may be dispersed on the surfaces of both conductive carbon layers. However, in order to exhibit the drainage effect, the conductive particles are preferably present on the surface of the conductive carbon layer to be disposed on the MEA side (reaction surface side).
　［中間層］
　図４３に示すように、本実施形態において、セパレータ４０５は、中間層４５６を有する。この中間層４５６は、金属基材４５２と導電性炭素層４５４との密着性を向上させるという機能や、金属基材４５２からのイオンの溶出を防止するという機能を有する。特に、Ｒ値が上述した好ましい範囲の上限値を超える場合に、中間層４５６を設けることによる効果は顕著に発現する。ただし、Ｒ値が上述した好ましい範囲に含まれる場合であっても中間層が設けられる。他の観点から、中間層４５６の設置による上述した作用効果は、金属基材４５２がアルミニウム又はその合金から構成される場合にも顕著に発現する。 [Middle layer]
As shown in FIG. 43, in this embodiment, the separator 405 has an intermediate layer 456. The intermediate layer 456 has a function of improving the adhesion between the metal base material 452 and the conductive carbon layer 454 and a function of preventing elution of ions from the metal base material 452. In particular, when the R value exceeds the upper limit value of the preferable range described above, the effect of providing the intermediate layer 456 is remarkably exhibited. However, the intermediate layer is provided even when the R value is included in the preferred range described above. From another point of view, the above-described operational effects due to the installation of the intermediate layer 456 are remarkably exhibited even when the metal substrate 452 is made of aluminum or an alloy thereof.
　中間層４５６を構成する材料としては、上記の密着性を付与するものであれば特に制限はないが、第一実施形態の中間層３２と同様の材料を使用することができる。また、中間層４５６の厚さは特に制限されないが、第一実施形態の中間層３２と同様の厚さとすることができる。さらに、中間層４５６の構造も特に制限されないが、第一実施形態の中間層３２と同様の柱状構造とすることができる。さらに、第一実施形態と同様に、中間層の熱膨張率（αｍｉｄ）、金属基材の熱膨張率（αｓｕｂ）、及び導電性炭素層の熱膨張率（αｃ）は、数式２の関係を満足することが好ましい。 The material constituting the intermediate layer 456 is not particularly limited as long as it provides the above-mentioned adhesion, but the same material as the intermediate layer 32 of the first embodiment can be used. The thickness of the intermediate layer 456 is not particularly limited, but can be the same thickness as the intermediate layer 32 of the first embodiment. Further, the structure of the intermediate layer 456 is not particularly limited, but can be a columnar structure similar to the intermediate layer 32 of the first embodiment. Further, as in the first embodiment, the thermal expansion coefficient (α mid ) of the intermediate layer, the thermal expansion coefficient (α sub ) of the metal base material, and the thermal expansion coefficient (α c ) of the conductive carbon layer are expressed by Equation 2. It is preferable to satisfy this relationship.
　なお、中間層は、金属基材の少なくとも一方の表面上に存在すれば良い。ただし、導電性炭素層が金属基材の一方の主表面にのみ存在する場合には、中間層は、金属基材と導電性炭素層との間に存在する。また、導電性炭素層は、上述したように金属基材の両面に存在する場合もある。このような場合には、中間層は、金属基材と双方の導電性炭素層との間にそれぞれ介在することが好ましい。金属基材といずれか一方の導電性炭素層との間にのみ中間層が存在する場合には、当該中間層は、ＰＥＦＣにおいてＭＥＡ側に配置されることとなる導電性炭素層と金属基材との間に存在することが好ましい。 The intermediate layer may be present on at least one surface of the metal substrate. However, when the conductive carbon layer exists only on one main surface of the metal substrate, the intermediate layer exists between the metal substrate and the conductive carbon layer. In addition, the conductive carbon layer may be present on both surfaces of the metal substrate as described above. In such a case, it is preferable that the intermediate layer is interposed between the metal base and both conductive carbon layers. When the intermediate layer exists only between the metal substrate and one of the conductive carbon layers, the intermediate layer is disposed on the MEA side in the PEFC and the conductive carbon layer and the metal substrate. It is preferable that it exists between.
　［ガス拡散層］
　ガス拡散層（アノードガス拡散層４０４ａ、カソードガス拡散層４０４ｂ）は、複数の空孔を有するガス拡散基体から構成され、セパレータ（アノードセパレータ５ａ及びカソードセパレータ５ｂ）に隣接して配置される。ガス拡散層は、セパレータのガス流路（６ａ、６ｃ）を介して供給されたガス（燃料ガス又は酸化剤ガス）の触媒層（３ａ、３ｂ）への拡散を促進する機能、及び電子伝導パスとしての機能を有する。本実施形態に係るガス拡散層としては、第一実施形態で説明したガス拡散層を用いることもできるし、また第四実施形態で説明したガス拡散層を用いることもできる。 [Gas diffusion layer]
The gas diffusion layers (anode gas diffusion layer 404a and cathode gas diffusion layer 404b) are composed of a gas diffusion substrate having a plurality of holes, and are disposed adjacent to the separators (anode separator 5a and cathode separator 5b). The gas diffusion layer has a function of promoting diffusion of gas (fuel gas or oxidant gas) supplied through the gas flow paths (6a, 6c) of the separator to the catalyst layers (3a, 3b), and an electron conduction path. As a function. As the gas diffusion layer according to the present embodiment, the gas diffusion layer described in the first embodiment can be used, or the gas diffusion layer described in the fourth embodiment can be used.
　次に、導電部材を製造するための好ましい実施形態を記載するが、本発明の技術的範囲は下記の形態のみには限定されない。また、導電部材４０８を構成するセパレータ４０５及びガス拡散層４０４の各構成要素の材質などの諸条件については、上述した通りであるため、ここでは説明を省略する。 Next, a preferred embodiment for manufacturing a conductive member will be described, but the technical scope of the present invention is not limited to the following embodiment. In addition, since various conditions such as the material of each component of the separator 405 and the gas diffusion layer 404 constituting the conductive member 408 are as described above, description thereof is omitted here.
　上記導電部材の製造方法は、金属基材の少なくとも一方の主表面に導電性炭素層を成膜する工程と、前記導電性炭素層の表面に親水導電性粒子を分散させる工程と、前記導電性粒子を分散させた領域に接触するようにガス拡散層を配置させる工程と、を有する。そして、前記導電性粒子の分散を、スパッタリング法により行う。 The method for producing a conductive member includes a step of forming a conductive carbon layer on at least one main surface of a metal substrate, a step of dispersing hydrophilic conductive particles on the surface of the conductive carbon layer, and the conductive property. And a step of disposing a gas diffusion layer so as to be in contact with the region where the particles are dispersed. Then, the conductive particles are dispersed by a sputtering method.
　まず、金属基材の構成材料として、所望の厚さのステンレス板などを準備する。次いで、第一実施形態と同様に、適当な溶媒を用いて、準備した金属基材の表面の脱脂及び洗浄処理を行う。続いて、金属基材の表面（両面）に形成されている酸化皮膜の除去を行う。酸化皮膜を除去するための手法としては、第一実施形態と同様の方法で行う。 First, a stainless steel plate having a desired thickness is prepared as a constituent material of the metal substrate. Next, as in the first embodiment, the surface of the prepared metal substrate is degreased and cleaned using an appropriate solvent. Subsequently, the oxide film formed on the surface (both sides) of the metal substrate is removed. As a method for removing the oxide film, the same method as in the first embodiment is used.
　次に、上記の処理を施した金属基材の構成材料の表面に、導電性炭素層を成膜する。例えば、上述した導電性炭素層の構成材料（例えば、グラファイト）をターゲットとして、金属基材上に導電性炭素を含む層を原子レベルで積層することにより、導電性炭素層を形成することができる。これにより、直接付着した導電性炭素層と金属基材との界面及びその近傍は、分子間力や僅かな炭素原子の進入によって、長期間にわたって密着性が保持される。導電性炭素を積層するのに好適に用いられる手法としては、第一実施形態と同様の手法を用いることができる。 Next, a conductive carbon layer is formed on the surface of the constituent material of the metal substrate subjected to the above-described treatment. For example, a conductive carbon layer can be formed by laminating a layer containing conductive carbon on a metal substrate at an atomic level using the above-described constituent material of the conductive carbon layer (for example, graphite) as a target. . As a result, the adhesion between the interface between the conductive carbon layer and the metal substrate directly attached and the vicinity thereof is maintained for a long period of time due to intermolecular forces and the entry of a few carbon atoms. As a technique suitably used for laminating conductive carbon, the same technique as in the first embodiment can be used.
　次に、上記の処理を施した導電性炭素層の表面の全体又は一部に、導電性粒子を分散させる。上述したように、導電性粒子は導電性炭素層の表面上のガス拡散層と接触する領域に分散されていれば良い。導電性炭素層の表面の一部にのみ導電性粒子を分散させるには、例えば、マスクを形成させて所望の部分に選択的に導電性粒子を分散させれば良い。導電性粒子を分散させる手法としては、第三実施形態の導電性粒子と同様の手法を用いることができる。なかでも、スパッタリング法又はメッキ法を用いることが好ましい。 Next, conductive particles are dispersed on the whole or a part of the surface of the conductive carbon layer subjected to the above treatment. As described above, the conductive particles only have to be dispersed in a region in contact with the gas diffusion layer on the surface of the conductive carbon layer. In order to disperse the conductive particles only on a part of the surface of the conductive carbon layer, for example, a mask may be formed and the conductive particles may be selectively dispersed in a desired portion. As a method of dispersing the conductive particles, the same method as that of the conductive particles of the third embodiment can be used. Among these, it is preferable to use a sputtering method or a plating method.
　スパッタリング法を用いる場合には、密着性の高い導電性粒子の分散構造が得られる。また、導電性炭素層の成膜（スパッタリング）に続いて、ターゲットを変更するだけで連続的に導電性粒子を分散させることができるため好ましい。スパッタリング条件としては上記したような導電性粒子の分散構造が形成できるような条件であれば特に制限されない。ただし、スパッタリング時に金属基材に対して負のバイアス電圧を印加すると良い。一例として、印加される電圧の大きさは、好ましくは５０～５００Ｖであり、より好ましくは１００～３００Ｖである。なお、その他の条件等の具体的な形態は特に制限されず、従来公知の知見が適宜参照される。 When the sputtering method is used, a dispersed structure of conductive particles having high adhesion can be obtained. Moreover, it is preferable because the conductive particles can be dispersed continuously by simply changing the target following the formation (sputtering) of the conductive carbon layer. The sputtering conditions are not particularly limited as long as the above-described conductive particle dispersion structure can be formed. However, it is preferable to apply a negative bias voltage to the metal substrate during sputtering. As an example, the magnitude of the applied voltage is preferably 50 to 500V, more preferably 100 to 300V. In addition, the specific forms such as other conditions are not particularly limited, and conventionally known knowledge is appropriately referred to.
　一方、メッキ法を用いる場合には、高被覆率で導電性粒子を分散させることができる。また、プロセスをＲｏｌｌ－ｔｏ－Ｒｏｌｌ方式で行うことが可能となるため、量産化が可能となる。メッキ条件としては上記したような導電性粒子の分散構造が形成できるような条件であれば特に制限されず、使用される導電性粒子の種類や量などによって異なる。例えば、メッキ処理条件としては、電流密度が０．２５～５Ａ／ｄｍ２、浴温度４５～５５℃、電析時間１０秒～１００分前後である。ただし、析出時間は対極のサイズや形状等によっても変わるため、適宜調整することができる。このような条件によって、所望の導電性粒子の分散構造が容易に形成される。 On the other hand, when the plating method is used, the conductive particles can be dispersed with a high coverage. Further, since the process can be performed by the Roll-to-Roll method, mass production becomes possible. The plating conditions are not particularly limited as long as the above-described conductive particle dispersion structure can be formed, and vary depending on the type and amount of the conductive particles used. For example, plating conditions are a current density of 0.25 to 5 A / dm 2 , a bath temperature of 45 to 55 ° C., and an electrodeposition time of about 10 seconds to about 100 minutes. However, since the deposition time varies depending on the size and shape of the counter electrode, it can be adjusted as appropriate. Under such conditions, a desired dispersed structure of conductive particles is easily formed.
　なお、導電性粒子の被覆率や粒子径は、予めスパッタ時間又はメッキ時間などの条件と分散量との関係をあらかじめ把握した上で、これらを制御することにより所望の範囲に設定することができる。また、上述したように被覆率は導電性粒子を分散させる導電性炭素層の材質や粒子の分散手法によっても異なるため、導電性炭素層の材質と被覆形態との関係をあらかじめ把握しておく必要がある。例えば、導電性炭素及び樹脂を複合化させた複合材を用いた場合に、メッキ法を用いて導電性粒子を分散させると、導電性粒子は炭素の表面には吸着するが、樹脂表面には吸着しない。このため、このような複合材を用いた場合には、複合材に含まれる樹脂量についても考慮した上で被覆率を制御する必要がある。 Note that the coverage and particle diameter of the conductive particles can be set to a desired range by previously grasping the relationship between the dispersion amount and conditions such as sputtering time or plating time in advance. . In addition, as described above, since the coverage varies depending on the material of the conductive carbon layer in which the conductive particles are dispersed and the method of dispersing the particles, it is necessary to grasp in advance the relationship between the material of the conductive carbon layer and the coating form There is. For example, in the case of using a composite material in which conductive carbon and a resin are combined, if the conductive particles are dispersed using a plating method, the conductive particles are adsorbed on the surface of the carbon, but the resin surface is adsorbed. Does not adsorb. For this reason, when such a composite material is used, it is necessary to control the coverage rate in consideration of the amount of resin contained in the composite material.
　金属基材４５２の一方又は両方の主表面に形成された導電性炭素層４５４の表面に対して上記処理を行うことで、金属基材４５２の一方又は両方の主表面に導電性炭素層４５４が形成され、かつ導電性炭素層４５４の表面に親水導電性粒子４５７が分散されたセパレータが製造される。 By performing the above-described treatment on the surface of the conductive carbon layer 454 formed on one or both main surfaces of the metal substrate 452, the conductive carbon layer 454 is formed on one or both main surfaces of the metal substrate 452. A separator that is formed and has hydrophilic conductive particles 457 dispersed on the surface of the conductive carbon layer 454 is manufactured.
　なお、中間層４５６を有する、図４３に示す形態のセパレータを製造するには、上述した導電性炭素層の成膜工程の前に、金属基材の少なくとも一方の主表面に中間層を成膜する工程を行う。この際、中間層を成膜する手法としては、導電性炭素層の成膜について上述したのと同様の手法が採用される。ただし、ターゲットを中間層の構成材料に変更する必要がある。続いて、成膜された中間層上に、導電性炭素層を成膜する工程及び導電性粒子を分散させる工程を行えば良い。中間層の表面に導電性炭素層を成膜する手法も、金属基材の表面への導電性炭素層の成膜について上述したのと同様の手法が採用される。 In order to manufacture the separator having the intermediate layer 456 in the form shown in FIG. 43, the intermediate layer is formed on at least one main surface of the metal substrate before the conductive carbon layer forming step described above. The process to do is performed. At this time, as the method for forming the intermediate layer, the same method as described above for the formation of the conductive carbon layer is employed. However, it is necessary to change the target to the constituent material of the intermediate layer. Subsequently, a step of forming a conductive carbon layer and a step of dispersing conductive particles may be performed on the formed intermediate layer. As the method for forming the conductive carbon layer on the surface of the intermediate layer, the same method as described above for the formation of the conductive carbon layer on the surface of the metal substrate is employed.
　そして、上記の方法により得られるセパレータの上に、ガス拡散基体を積層させることにより、セパレータとガス拡散層とが積層されてなる導電部材を得る。この際、導電性粒子を分散させた領域にガス拡散層が接触するようにガス拡散層を積層させる。 Then, a conductive member formed by laminating the separator and the gas diffusion layer is obtained by laminating the gas diffusion base on the separator obtained by the above method. At this time, the gas diffusion layer is laminated so that the gas diffusion layer is in contact with the region where the conductive particles are dispersed.
　本実施形態の導電部材は、第一実施形態の導電部材と同様に、ＰＥＦＣ以外にも、ＰＡＦＣ、ＭＣＦＣ、ＳＯＦＣ又はＡＦＣなどの各種の燃料電池を構成する導電部材としても使用可能である。また、導電部材以外にも、導電性・耐食性の両立が求められている各種の用途に用いられる。他の好ましい形態において、本実施形態の導電部材は、湿潤環境及び通電環境の下で使用される。このような環境下で用いると、導電性及び排水性の両立を図るという本発明の作用効果が顕著に発現する。 The conductive member of the present embodiment can be used as a conductive member constituting various fuel cells such as PAFC, MCFC, SOFC, and AFC in addition to PEFC, similarly to the conductive member of the first embodiment. Further, in addition to the conductive member, it is used for various applications that require both conductivity and corrosion resistance. In another preferred embodiment, the conductive member of the present embodiment is used in a wet environment and an energized environment. When used in such an environment, the effect of the present invention of achieving both conductivity and drainage remarkably appears.
　以下、本実施形態に係る導電部材の効果を、実施例及び比較例を用いて説明するが、本発明の技術的範囲はこれらの実施例に限定されない。 Hereinafter, the effects of the conductive member according to the present embodiment will be described using examples and comparative examples, but the technical scope of the present invention is not limited to these examples.
　［実施例V－１］
　セパレータを構成する金属基材の構成材料として、ステンレス板（ＳＵＳ３１６Ｌ）を準備した。なお、このステンレス板の厚さは、１００μｍである。このステンレス板を、前処理としてエタノール液中で３分間超音波洗浄した。次いで、洗浄したステンレス板を真空チャンバ内に設置し、Ａｒガスによるイオンボンバード処理を行って、表面の酸化皮膜を除去した。なお、真空チャンバの真空度は１０－３Ｐａ程度とし、Ａｒガスの圧力は０．１～１Ｐａ程度とした。また、上述した前処理及びイオンボンバード処理は、いずれもステンレス板の両面に対して行った。 [Example V-1]
A stainless steel plate (SUS316L) was prepared as a constituent material of the metal substrate constituting the separator. The stainless steel plate has a thickness of 100 μm. This stainless steel plate was subjected to ultrasonic cleaning in an ethanol solution for 3 minutes as a pretreatment. Next, the cleaned stainless steel plate was placed in a vacuum chamber, and ion bombardment with Ar gas was performed to remove the oxide film on the surface. The vacuum degree of the vacuum chamber was about 10 −3 Pa, and the Ar gas pressure was about 0.1 to 1 Pa. The pretreatment and ion bombardment described above were both performed on both surfaces of the stainless steel plate.
　続いて、アンバランスドマグネトロンスパッタリング法により、中間層を形成した。具体的には、Ｃｒをターゲットとして、ステンレス板に対して５０Ｖの大きさの負のバイアス電圧を印加しながら、ステンレス板の両面にそれぞれＣｒからなる中間層を形成した。なお、中間層の厚さは０．２μｍであった。 Subsequently, an intermediate layer was formed by an unbalanced magnetron sputtering method. Specifically, using Cr as a target, an intermediate layer made of Cr was formed on both surfaces of the stainless steel plate while applying a negative bias voltage of 50 V to the stainless steel plate. The intermediate layer had a thickness of 0.2 μm.
　次に、ＵＢＭＳ法により、導電性炭素層（多結晶グラファイト層）を形成した。具体的には、
固体グラファイトをターゲットとして、ステンレス板に対して１００Ｖの大きさの負のバイアス電圧を印加しながら、ステンレス板の両面の中間層の上にそれぞれ導電性炭素層を形成した。なお、導電性炭素層の厚さは０．２μｍであった。 Next, a conductive carbon layer (polycrystalline graphite layer) was formed by the UBMS method. In particular,
Using solid graphite as a target, conductive carbon layers were formed on the intermediate layers on both sides of the stainless steel plate while applying a negative bias voltage of 100 V to the stainless steel plate. The thickness of the conductive carbon layer was 0.2 μm.
　さらに、ＵＢＭＳ法により、導電性粒子の原料であるＡｕをターゲットとして、ステンレス板に対して１００Ｖの大きさの負のバイアス電圧を印加しながら、ステンレス板の両面の導電性炭素層の上に、導電性粒子を分散させた。これにより、セパレータ（１）を作製した。 Furthermore, by applying a negative bias voltage of 100 V to the stainless steel plate with Au serving as a raw material of the conductive particles as a target by the UBMS method, on the conductive carbon layers on both surfaces of the stainless steel plate, Conductive particles were dispersed. This produced the separator (1).
　［実施例V－２］
　導電性粒子（Ａｕ）のスパッタリング時間を変更すること以外は、上述した実施例V－１と同様の手法により、セパレータ（２）を作製した。 [Example V-2]
A separator (2) was produced in the same manner as in Example V-1, except that the sputtering time of the conductive particles (Au) was changed.
　［実施例V－３］
　導電性粒子（Ａｕ）のスパッタリング時間を変更すること以外は、上述した実施例V－１と同様の手法により、セパレータ（３）を作製した。 [Example V-3]
A separator (3) was produced in the same manner as in Example V-1, except that the sputtering time of the conductive particles (Au) was changed.
　［比較例V－１］
　導電性炭素層の表面に導電性粒子を分散させなかったこと以外は、上述した実施例V－１と同様の手法により、セパレータ（４）を作製した。 [Comparative Example V-1]
A separator (4) was produced in the same manner as in Example V-1, except that the conductive particles were not dispersed on the surface of the conductive carbon layer.
　［実施例V－４］
　導電性炭素層として、グラファイトブロック（高結晶性グラファイト）をそのまま用いたこと以外は、上述した実施例V－１と同様の手法により、セパレータ（５）を作製した。 [Example V-4]
A separator (5) was produced in the same manner as in Example V-1, except that the graphite block (highly crystalline graphite) was used as it was as the conductive carbon layer.
　［比較例V－２］
　導電性炭素層の表面に導電性粒子を分散させなかったこと以外は、上述した実施例V－４と同様の手法により、セパレータ（６）を作製した。 [Comparative Example V-2]
A separator (6) was produced in the same manner as in Example V-4 described above, except that the conductive particles were not dispersed on the surface of the conductive carbon layer.
　［ＳＥＭ観察・被覆率測定］
　上記の各実施例及び各比較例において作成したセパレータ（１）～（６）について、導電性炭素層の表面を走査型電子顕微鏡により撮影した。 [SEM observation / coverage measurement]
For the separators (1) to (6) prepared in each of the above examples and comparative examples, the surface of the conductive carbon layer was photographed with a scanning electron microscope.
　これらのうち、セパレータ（１）及び（２）における導電性粒子（Ａｕ）が分散された導電性炭素層の表面のＳＥＭ写真を図４５及び図４６に示す。図４５及び図４６より、導電性粒子（Ａｕ）が導電性炭素層の表面に均質に分散されていることが確認される。導電性粒子や金属酸化物を分散させなかったセパレータ（４）以外のセパレータについては、図４５及び図４６と同様に、導電性粒子（Ａｕ）が導電性炭素層の表面に均質に分散されていることを確認した。 Among these, FIGS. 45 and 46 show SEM photographs of the surface of the conductive carbon layer in which the conductive particles (Au) in the separators (1) and (2) are dispersed. 45 and 46, it is confirmed that the conductive particles (Au) are uniformly dispersed on the surface of the conductive carbon layer. As for the separators other than the separator (4) in which the conductive particles and the metal oxide are not dispersed, the conductive particles (Au) are uniformly dispersed on the surface of the conductive carbon layer as in FIGS. 45 and 46. I confirmed.
　また、ＳＥＭ写真から、各セパレータの表面に存在する分散粒子（導電性粒子又は金属酸化物）の平均粒子径及び分散粒子間の平均距離を算出した。 Further, from the SEM photograph, the average particle diameter of the dispersed particles (conductive particles or metal oxide) present on the surface of each separator and the average distance between the dispersed particles were calculated.
　また、ＥＤＸにより、導電性炭素層表面に存在する元素の面内分布を調査した。そして、カーボンの占める領域を緑色、導電性粒子（Ａｕ）の占める領域を赤色として２値化し、画像処理によって赤色の占める割合を計算し、この値を被覆率（％）として求めた。各セパレータにおける導電性粒子の粒子径及び被覆率を表６に示す。 Also, the in-plane distribution of elements present on the surface of the conductive carbon layer was investigated by EDX. Then, the area occupied by carbon was binarized as green, and the area occupied by conductive particles (Au) was binarized, and the ratio occupied by red was calculated by image processing, and this value was obtained as the coverage (%). Table 6 shows the particle diameter and coverage of the conductive particles in each separator.
　［ＡＥＳ（オージェ電子分光法）による元素濃度プロファイル解析］
　実施例V－２及び比較例V－１で作製したセパレータ（２）及び（４）について、セパレータの積層方向の元素濃度プロファイルをＡＥＳにより測定した。図４７Ａ及び図４７Ｂに、セパレータ（２）及び（４）に関する、導電性炭素層の表面から深さ方向における元素分布を示す。比較例V－１のセパレータ（４）では、導電性炭素層の表面に導電性粒子は存在しないが、実施例V－２のセパレータ（２）では、導電性炭素層の表層に導電性粒子（Ａｕ）が存在していることが確認された。つまり、導電性粒子（Ａｕ）は導電性炭素層（Ｃ）の表層に存在していた。なお、上記ＡＥＳ測定は、第三実施形態の実施例と同様の条件で行った。 [Element concentration profile analysis by AES (Auger electron spectroscopy)]
For the separators (2) and (4) produced in Example V-2 and Comparative Example V-1, the element concentration profile in the stacking direction of the separator was measured by AES. 47A and 47B show element distributions in the depth direction from the surface of the conductive carbon layer, regarding the separators (2) and (4). In the separator (4) of Comparative Example V-1, no conductive particles are present on the surface of the conductive carbon layer. However, in the separator (2) of Example V-2, conductive particles ( Au) was confirmed to be present. That is, the conductive particles (Au) were present on the surface layer of the conductive carbon layer (C). The AES measurement was performed under the same conditions as in the example of the third embodiment.
　［接触抵抗の測定］
　上記の各実施例及び比較例において作製したセパレータについて、セパレータの積層方向の接触抵抗の測定を行った。具体的には、図１１に示すように、作製したセパレータ５を１対のガス拡散層４ａ、４ｂで挟持し、得られた積層体をさらに１対の電極（触媒層３ａ、３ｂ）で挟持し、その両端に電源を接続し、１ＭＰａの荷重で保持して、測定装置を構成した。ガス拡散層としては、カーボンファイバ（東レ製、平均繊維径７μｍ）を用いた。この測定装置に１Ａの定電流を流し、その際の電圧値から、積層体の接触抵抗値を算出した。得られた結果を下記の表６に示す。また、表６に示す接触抵抗に関する結果に対応するグラフを図４８に示す。 [Measurement of contact resistance]
For the separators produced in each of the above examples and comparative examples, the contact resistance in the stacking direction of the separators was measured. Specifically, as shown in FIG. 11, the produced separator 5 is sandwiched between a pair of gas diffusion layers 4a and 4b, and the resulting laminate is further sandwiched between a pair of electrodes (catalyst layers 3a and 3b). And the power supply was connected to the both ends, and it hold | maintained with the load of 1 MPa, and comprised the measuring apparatus. As the gas diffusion layer, carbon fiber (manufactured by Toray, average fiber diameter: 7 μm) was used. A constant current of 1 A was passed through this measuring device, and the contact resistance value of the laminate was calculated from the voltage value at that time. The results obtained are shown in Table 6 below. Further, FIG. 48 shows a graph corresponding to the results regarding the contact resistance shown in Table 6.
　表６及び図４８に示すように、実施例において作製したセパレータの場合には、比較例の場合と比べて、接触抵抗が小さい値に抑えられており、被覆率が１％以上である場合には、接触抵抗が有意に低減されていることがわかる。さらに、被覆率が１０％以上である場合には、接触抵抗が極めて小さい値に抑えられることが確認された。 As shown in Table 6 and FIG. 48, in the case of the separator manufactured in the example, the contact resistance is suppressed to a smaller value than in the comparative example, and the coverage is 1% or more. It can be seen that the contact resistance is significantly reduced. Furthermore, it was confirmed that the contact resistance can be suppressed to a very small value when the coverage is 10% or more.
　また、多結晶グラファイトを用いた場合（実施例V－１～V－３）は、グラファイトブロックを用いた場合（実施例V－４）に比べて、低被覆率で顕著に接触抵抗を減少することができることが確認される。多結晶グラファイトの場合には、グラファイトブロックに比べて表面粗さが小さいため、ガス拡散基体との接点を多く確保することができ、これにより一層の抵抗低減効果が得られたためであると推測される。 Further, when polycrystalline graphite is used (Examples V-1 to V-3), contact resistance is remarkably reduced at a low coverage compared to the case where graphite blocks are used (Example V-4). It is confirmed that it can. In the case of polycrystalline graphite, since the surface roughness is smaller than that of the graphite block, it is possible to secure a large number of contacts with the gas diffusion substrate, and this is presumed to have resulted in a further resistance reduction effect. The
　［接触角の測定］
　上記の各実施例及び比較例において作製したセパレータ（１）～（６）について、ＪＩＳ　Ｋ６７６８に基づき、導電性粒子の分散された導電性炭素層の表面における水の接触角を測定した。結果を得られた結果を下記の表６に示す。また、表６に示す接触角に関する結果に対応するグラフを図４９に示す。 [Measurement of contact angle]
With respect to the separators (1) to (6) produced in each of the above examples and comparative examples, the contact angle of water on the surface of the conductive carbon layer in which the conductive particles were dispersed was measured based on JIS K6768. The results obtained are shown in Table 6 below. FIG. 49 shows a graph corresponding to the contact angle results shown in Table 6.
　この結果から、各実施例において作製した被覆率が１％以上であるセパレータの場合には、比較例の場合と比べて、導電性炭素層の表面における水の接触角が７０°以下に抑えられていることがわかる。さらに、被覆率が１０％以上である場合には、接触角の値が減少し、親水性が極めて向上することが確認された。 From this result, in the case of the separator having a coverage of 1% or more produced in each example, the contact angle of water on the surface of the conductive carbon layer is suppressed to 70 ° or less compared to the case of the comparative example. You can see that Furthermore, it was confirmed that when the coverage is 10% or more, the value of the contact angle is decreased and the hydrophilicity is extremely improved.
　接触角については、多結晶グラファイトを用いた場合（実施例V－１）においては、４％程度の低被覆率で接触角を７０°以下に低下させることが確認された。また、グラファイトブロックを用いた場合（実施例V－４）においても、４％程度の低被覆率で接触角を７０°以下に低下させることが確認された。 Regarding the contact angle, when polycrystalline graphite was used (Example V-1), it was confirmed that the contact angle was reduced to 70 ° or less with a low coverage of about 4%. It was also confirmed that the contact angle was reduced to 70 ° or less at a low coverage of about 4% even when a graphite block was used (Example V-4).
　［Ｒ値の測定］
　上記の各実施例及び比較例において作製したセパレータについて、導電性炭素層のＲ値の測定を行った。具体的には、まず、顕微ラマン分光器を用いて、導電性炭素層のラマンスペクトルを計測した。そして、１３００～１４００ｃｍ－１に位置するバンド（Ｄバンド）のピーク強度（ＩＤ）と、１５００～１６００ｃｍ－１に位置するバンド（Ｇバンド）のピーク強度（ＩＧ）とのピーク面積比（ＩＤ／ＩＧ）を算出して、Ｒ値とした。得られた結果を下記の表６に示す。 [Measurement of R value]
About the separator produced in said each Example and comparative example, the R value of the conductive carbon layer was measured. Specifically, first, the Raman spectrum of the conductive carbon layer was measured using a microscopic Raman spectrometer. Then, 1300 ~ 1400 cm peak intensity of the bands (D-band) located -1 (I D), the peak area ratio of the peak intensity (I G) of band (G-band) located 1500 ~ 1600 cm -1 ( I D / I G ) was calculated and used as the R value. The results obtained are shown in Table 6 below.
　表６に示すように、実施例V－１～V－３及び比較例V－１において作製したセパレータにおける導電性炭素層のＲ値は、いずれも１．３以上であった。一方、実施例V－４及び比較例V－２において作製したセパレータにおける導電性炭素層のＲ値は、いずれも１．３未満であった。表６から、Ｒ値が１．３以上である実施例V－１において作製したセパレータを用いた場合には、Ｒ値以外は同様の条件で作成したＲ値が１．３未満である実施例V－４の場合と比べて、接触抵抗をより小さい値に抑えられることが確認された。 As shown in Table 6, the R values of the conductive carbon layers in the separators produced in Examples V-1 to V-3 and Comparative Example V-1 were all 1.3 or more. On the other hand, the R values of the conductive carbon layers in the separators produced in Example V-4 and Comparative Example V-2 were both less than 1.3. From Table 6, when the separator prepared in Example V-1 having an R value of 1.3 or more was used, an example in which the R value prepared under the same conditions except for the R value was less than 1.3. Compared with the case of V-4, it was confirmed that the contact resistance can be suppressed to a smaller value.
Figure JPOXMLDOC01-appb-T000008
Figure JPOXMLDOC01-appb-T000008
　＊１：実施例３で作成したセパレータは被覆率が高いため、隣接する導電性粒子（Ａｕ）が結合し、独立した粒子を確認することができなかった。このため、平均粒子径及び平均粒子間距離を算出することができなかった。 * 1: Since the separator prepared in Example 3 had a high coverage, adjacent conductive particles (Au) were bonded, and independent particles could not be confirmed. For this reason, the average particle diameter and the average interparticle distance could not be calculated.
　特願２００８－３００１３３号 (出願日：２００８年１１月２５日)、特願２００８－３０１３０９号 (出願日：２００８年１１月２６日)、特願２００８－３０３２１７号 (出願日：２００８年１１月２７日)、特願２００８－３０３２１９号 (出願日：２００8年１１月２７日)、特願２００８－３０３２２３号 (出願日：２００８年１１月２７日)及び特願２００９－１４２６００号 (出願日：２００９年６月１５日)の全内容は、ここに援用される。 Japanese Patent Application No. 2008-300313 (Application Date: November 25, 2008), Japanese Patent Application No. 2008-301309 (Application Date: November 26, 2008), Japanese Patent Application No. 2008-303217 (Application Date: November 2008) 27), Japanese Patent Application No. 2008-303219 (Application Date: November 27, 2008), Japanese Patent Application No. 2008-303223 (Application Date: November 27, 2008) and Japanese Patent Application No. 2009-142600 (Application Date: The entire contents of June 15, 2009) are incorporated herein.
　以上、実施の形態及び実施例に沿って本発明の内容を説明したが、本発明はこれらの記載に限定されるものではなく、種々の変形及び改良が可能であることは、当業者には自明である。具体的には、上記第一実施形態～第五実施形態の構成を適宜組み合わせることができる。 The contents of the present invention have been described according to the embodiments and examples. However, the present invention is not limited to these descriptions, and various modifications and improvements can be made by those skilled in the art. It is self-explanatory. Specifically, the configurations of the first to fifth embodiments can be combined as appropriate.
　本発明の導電部材によれば、導電性炭素層の一方の面から他方の面への導電パスが確保されることにより、優れた導電性を十分に確保しつつ、耐食性がより一層向上した導電部材が提供される。 According to the conductive member of the present invention, by ensuring a conductive path from one surface of the conductive carbon layer to the other surface, it is possible to sufficiently improve the corrosion resistance while sufficiently ensuring excellent conductivity. A member is provided.
　１　　単セル
　２　　固体高分子電解質膜
　３　　触媒層
　４　　ガス拡散層
　５　　セパレータ
　６　　金属基材
　９　　膜電極接合体
　２０　　燃料電池スタック
　３１　　金属基材
　３２　　中間層
　３３　　導電性炭素層 DESCRIPTION OF SYMBOLS 1 Single cell 2 Solid polymer electrolyte membrane 3 Catalyst layer 4 Gas diffusion layer 5 Separator 6 Metal base material 9 Membrane electrode assembly 20 Fuel cell stack 31 Metal base material 32 Intermediate layer 33 Conductive carbon layer

Claims (15)

  1. 　基材と、
    　前記基材の少なくとも一方の表面に位置し、さらに導電性炭素を含む導電性炭素層と、
    　前記基材と導電性炭素層との間に介在する中間層と、
    　を有した導電構造体を備え、
    　前記導電性炭素層において、ラマン散乱分光分析により測定されたＤバンドピーク強度（ＩＤ）とＧバンドピーク強度（ＩＧ）との強度比Ｒ（ＩＤ／ＩＧ）が１．３以上であることを特徴とする導電部材。     A substrate;
    A conductive carbon layer located on at least one surface of the substrate and further containing conductive carbon;
    An intermediate layer interposed between the base material and the conductive carbon layer;
    A conductive structure having
    In the conductive carbon layer, the intensity ratio R (I D / I G ) between the D band peak intensity ( ID ) and the G band peak intensity (I G ) measured by Raman scattering spectroscopy is 1.3 or more. There is a conductive member.
  2. 　前記導電性炭素層において、ラマン散乱分光分析による回転異方性測定により測定された平均ピークが２回対称パターンを示すことを特徴とする請求項１に記載の導電部材。 2. The conductive member according to claim 1, wherein in the conductive carbon layer, an average peak measured by rotational anisotropy measurement by Raman scattering spectroscopy shows a two-fold symmetry pattern.
  3. 　前記中間層は柱状構造を有しており、さらに前記中間層の表面上に、前記導電性炭素層を構成する突起状粒子が存在していることを特徴とする請求項１又は２に記載の導電部材。 The said intermediate | middle layer has a columnar structure, Furthermore, the protruding particle | grains which comprise the said conductive carbon layer exist on the surface of the said intermediate | middle layer, The Claim 1 or 2 characterized by the above-mentioned. Conductive member.
  4. 　前記中間層は、クロム、チタン、これらの炭化物及び窒化物からなる群から選ばれる少なくとも一種を含有し、
    　前記基材は、鉄、チタン、銅及びアルミニウム並びにこれらの合金からなる群から選ばれる少なくとも一種を含有することを特徴とする請求項１乃至３のいずれか１項に記載の導電部材。     The intermediate layer contains at least one selected from the group consisting of chromium, titanium, carbides and nitrides thereof,
    4. The conductive member according to claim 1, wherein the base material contains at least one selected from the group consisting of iron, titanium, copper, aluminum, and alloys thereof. 5.
  5. 　前記中間層の断面における柱状構造の柱の太さが２０ｎｍ～５００ｎｍであり、
    　前記導電性炭素層のビッカース硬度がＨｖ１５００以下であることを特徴とする請求項１乃至４のいずれか１項に記載の導電部材。     The thickness of the columnar column in the cross section of the intermediate layer is 20 nm to 500 nm,
    5. The conductive member according to claim 1, wherein the conductive carbon layer has a Vickers hardness of Hv 1500 or less.
  6. 　金属板から構成される前記基材と前記中間層との間に介在する緻密バリア層をさらに備え、
    　前記緻密バリア層は、前記中間層に比べて低い結晶配向性を有し、かつ、前記中間層の平均結晶子径（Ｄ１）に対する前記緻密バリア層の平均結晶子径（Ｄ２）の比（Ｄ２／Ｄ１）が０．１以上１未満であることを特徴とする請求項１乃至５のいずれか１項に記載の導電部材。     Further comprising a dense barrier layer interposed between the base material composed of a metal plate and the intermediate layer,
    The dense barrier layer has a lower crystal orientation than the intermediate layer, and a ratio of an average crystallite diameter (D 2 ) of the dense barrier layer to an average crystallite diameter (D 1 ) of the intermediate layer. 6. The conductive member according to claim 1, wherein (D 2 / D 1 ) is not less than 0.1 and less than 1. 6.
  7. 　金属板から構成される前記基材と前記中間層との間に、導電性粒子を含む導電性補強層をさらに備え、
    　前記導電性粒子は、貴金属、貴金属を含む合金及びカーボンからなる群より選ばれる少なくとも一種を含有することを特徴とする請求項１乃至５のいずれか１項に記載の導電部材。     A conductive reinforcing layer containing conductive particles is further provided between the base material composed of a metal plate and the intermediate layer,
    The conductive member according to claim 1, wherein the conductive particles contain at least one selected from the group consisting of a noble metal, an alloy containing a noble metal, and carbon.
  8. 　前記導電性粒子の平均粒子径は、前記基材を構成する金属又は前記中間層を構成する材料が形成する酸化被膜の厚さ以上であることを特徴とする請求項７に記載の導電部材。 The conductive member according to claim 7, wherein an average particle diameter of the conductive particles is equal to or greater than a thickness of an oxide film formed by a metal constituting the base material or a material constituting the intermediate layer.
  9. 　前記導電性補強層及び中間層が、前記基材の厚さ方向に多数配置した柱状組織を有する柱状性材料を含み、
    　前記導電性粒子は、少なくとも前記導電性補強層の柱状性材料の表面及び前記基材と前記導電性補強層との間の界面に存在することを特徴とする請求項７又は８に記載の導電部材。     The conductive reinforcing layer and the intermediate layer include a columnar material having a columnar structure arranged in a large number in the thickness direction of the base material,
    The conductive particles according to claim 7 or 8, wherein the conductive particles are present at least on a surface of the columnar material of the conductive reinforcing layer and an interface between the base material and the conductive reinforcing layer. Element.
  10. 　前記導電性炭素層上に、金属、金属窒化物、金属炭化物及び金属酸化物からなる群から選ばれる少なくとも一種を含有する親水化層をさらに備え、
    　前記基材は、多孔質材料から構成されることを特徴とする請求項１乃至５のいずれか１項に記載の導電部材。     On the conductive carbon layer, further comprising a hydrophilic layer containing at least one selected from the group consisting of metal, metal nitride, metal carbide and metal oxide,
    The conductive member according to claim 1, wherein the base material is made of a porous material.
  11. 　前記多孔質材料は、炭素繊維、金属繊維及び有機繊維からなる群から選ばれる少なくとも一種を含有し、
    　前記炭素繊維は、ポリアクリロニトリル系又はピッチ系炭素繊維であって、黒鉛化された繊維を含まない炭素化された繊維であることを特徴とする請求項１０に記載の導電部材。     The porous material contains at least one selected from the group consisting of carbon fiber, metal fiber and organic fiber,
    11. The conductive member according to claim 10, wherein the carbon fiber is a polyacrylonitrile-based or pitch-based carbon fiber, and is a carbonized fiber that does not include graphitized fiber.
  12. 　複数の空孔を有するガス拡散基体を含み、さらに前記導電性炭素層と対向するように積層される燃料電池用ガス拡散層をさらに備え、
    　前記導電構造体は、燃料電池用セパレータであり、
    　前記導電性炭素層の表面であって前記ガス拡散層と接触する領域に、親水導電性粒子が分散されており、
    　前記親水導電性粒子の粒子径及び前記親水導電性粒子間の距離が、前記ガス拡散基体の空孔間距離以下であることを特徴とする請求項１乃至９のいずれか１項に記載の導電部材。     A gas diffusion layer for a fuel cell including a gas diffusion substrate having a plurality of pores, and further laminated to face the conductive carbon layer;
    The conductive structure is a fuel cell separator,
    Hydrophilic conductive particles are dispersed in the surface of the conductive carbon layer and in a region in contact with the gas diffusion layer,
    10. The conductive material according to claim 1, wherein a particle diameter of the hydrophilic conductive particles and a distance between the hydrophilic conductive particles are equal to or less than a distance between pores of the gas diffusion substrate. Element.
  13. 　前記ガス拡散基体が炭素繊維から構成され、
    　前記親水導電性粒子の粒子径及び前記親水導電性粒子間の距離が、前記炭素繊維の直径以下であることを特徴とする請求項１２に記載の導電部材。     The gas diffusion substrate is made of carbon fiber;
    The conductive member according to claim 12, wherein a particle diameter of the hydrophilic conductive particles and a distance between the hydrophilic conductive particles are equal to or less than a diameter of the carbon fiber.
  14. 　前記親水導電性粒子は、貴金属、貴金属を含む合金、導電性窒化物及び導電性酸化物からなる群より選ばれる少なくとも一種を含有することを特徴とする請求項１２又は１３に記載の導電部材。 The conductive member according to claim 12 or 13, wherein the hydrophilic conductive particles contain at least one selected from the group consisting of noble metals, alloys containing noble metals, conductive nitrides, and conductive oxides.
  15. 　請求項１乃至１４のいずれか１項に記載の導電部材を備える固体高分子形燃料電池。 A solid polymer fuel cell comprising the conductive member according to any one of claims 1 to 14.
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102082277A (en) * 2010-12-24 2011-06-01 上海交通大学 Metal gas diffusion layer used for fuel cell and preparation method thereof

Families Citing this family (35)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010061711A1 (en) * 2008-11-28 2010-06-03 日産自動車株式会社 Sealing structure and fuel cell comprising the sealing structure
US8999597B2 (en) * 2010-06-15 2015-04-07 Nissan Motor Co., Ltd. Fuel cell
JP5712518B2 (en) * 2010-07-16 2015-05-07 日産自動車株式会社 Manufacturing method of conductive member
EP3002075B1 (en) * 2011-08-25 2017-02-01 Panasonic Intellectual Property Management Co., Ltd. Manufacturing methods of joined body
KR200469114Y1 (en) * 2011-11-03 2013-09-23 세방전지(주) Fuel cell stack
US20140227631A1 (en) * 2013-02-09 2014-08-14 Youngha JUN Method for manufacturing corrosion resistant and conductive nano carbon coating layer and fuel cell bipolar plate thereby using stainless steel substrate
JP6220393B2 (en) * 2013-06-13 2017-10-25 東洋鋼鈑株式会社 Gold-plated coated stainless steel and method for producing gold-plated coated stainless steel
CN105556002B (en) * 2013-09-20 2018-03-20 东洋钢钣株式会社 Plate metal covering stainless steel material and plate the manufacture method of metal covering stainless steel material
WO2015045852A1 (en) * 2013-09-30 2015-04-02 日産自動車株式会社 Carbon powder for catalyst, catalyst using said carbon powder for catalyst, electrode catalyst layer, membrane electrode assembly, and fuel cell
JP6203286B2 (en) 2013-12-13 2017-09-27 新日鐵住金株式会社 Support carbon material and metal catalyst particle-supported carbon material for polymer electrolyte fuel cell, and production method
WO2015126139A1 (en) * 2014-02-19 2015-08-27 Samsung Electronics Co., Ltd. Wiring structure and electronic device employing the same
CA2966143C (en) 2014-10-29 2023-08-22 Nissan Motor Co., Ltd. Electrode catalyst for fuel cell, method for producing the same, electrode catalyst layer for fuel cell comprising the catalyst, and membrane electrode assembly for fuel cell and fuel cell using the catalyst or the catalyst layer
CN107004864B (en) * 2014-10-29 2018-07-13 日产自动车株式会社 Electrode catalyst for fuel cell layer and the fuel battery membrane electrode assembly and fuel cell for using the catalyst layer
CN105655002B (en) * 2014-11-27 2017-06-23 松下知识产权经营株式会社 Conductive material
US10003089B2 (en) 2015-02-11 2018-06-19 Ford Global Technologies, Llc Multilayer coating for corrosion resistant metal bipolar plate for a PEMFC
US10135077B2 (en) 2015-02-12 2018-11-20 Ford Global Technologies, Llc Corrosion resistant metal bipolar plate for a PEMFC including a radical scavenger
BR112017019072B1 (en) * 2015-03-16 2022-11-08 Calera Corporation ION EXCHANGE MEMBRANE AND ELECTROCHEMICAL METHOD
JP6464897B2 (en) 2015-04-08 2019-02-06 トヨタ自動車株式会社 Fuel cell stack
US10266954B2 (en) 2015-10-28 2019-04-23 Calera Corporation Electrochemical, halogenation, and oxyhalogenation systems and methods
US20180323447A1 (en) * 2015-11-10 2018-11-08 Nippon Steel & Sumitomo Metal Corporation Titanium product, separator and polymer electrolyte fuel cell
DE102016205049A1 (en) * 2016-03-24 2017-09-28 Schunk Bahn- Und Industrietechnik Gmbh Discharge device and method for dissipating electrostatic charges
CN109312384B (en) 2016-06-15 2022-12-30 伊士曼化工公司 Physical vapor deposition biosensor assembly
DE102016116632A1 (en) 2016-09-06 2018-03-08 Audi Ag Gas diffusion electrode and fuel cell with such a
KR102547063B1 (en) 2016-09-16 2023-06-22 이스트만 케미칼 컴파니 Biosensor electrodes fabricated by physical vapor deposition
EP3512958B1 (en) 2016-09-16 2022-04-06 Eastman Chemical Company Biosensor electrodes prepared by physical vapor deposition
JP6887100B2 (en) * 2016-12-26 2021-06-16 パナソニックＩｐマネジメント株式会社 Membrane electrode assembly and electrochemical hydrogen pump
JP6566331B2 (en) * 2017-04-17 2019-08-28 パナソニックＩｐマネジメント株式会社 Electrocatalyst layer for electrochemical device, membrane / electrode assembly for electrochemical device, electrochemical device, and method for producing electrode catalyst layer for electrochemical device
US11881549B2 (en) 2017-06-22 2024-01-23 Eastman Chemical Company Physical vapor deposited electrode for electrochemical sensors
JP2019133838A (en) * 2018-01-31 2019-08-08 トヨタ自動車株式会社 Fuel cell separator
CN109037723B (en) * 2018-07-23 2022-05-27 上海交通大学 Graphite microcrystalline carbon coating for fuel cell metal bipolar plate and application
JP7115450B2 (en) * 2019-09-30 2022-08-09 トヨタ自動車株式会社 Fuel cell unit cell
WO2022073035A1 (en) * 2020-10-02 2022-04-07 Battelle Energy Alliance, Llc Electrochemical cells including anodes comprising a protective layer, and related methods
KR102326257B1 (en) * 2021-05-31 2021-11-16 주식회사 포스코 Steel plate with excellent hydrophilicty and conductivity
KR102326258B1 (en) * 2021-05-31 2021-11-16 주식회사 포스코 Steel plate with excellent hydrophilicty and conductivity
CN113915390B (en) * 2021-09-22 2023-09-12 南京信息工程大学 Automatic drain valve based on membrane structure

Citations (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH1087396A (en) * 1996-09-10 1998-04-07 Sumitomo Electric Ind Ltd Hard carbon film
JPH1149506A (en) * 1997-07-31 1999-02-23 Kyocera Corp Ornamental member
JP2000067881A (en) * 1998-08-24 2000-03-03 Honda Motor Co Ltd Separator for fuel cell
JP2002327271A (en) * 2001-04-27 2002-11-15 Sumitomo Electric Ind Ltd Electroconductive hard carbon film
JP2004185998A (en) 2002-12-04 2004-07-02 Toyota Motor Corp Separator for fuel cell
JP2006286457A (en) 2005-04-01 2006-10-19 Toyota Motor Corp Manufacturing method of fuel cell separator
JP2007134107A (en) 2005-11-09 2007-05-31 Toyota Motor Corp Separator for fuel cell, its manufacturing method and fuel cell
JP2007165275A (en) * 2005-04-28 2007-06-28 Kurimoto Ltd Separator, manufacturing method of separator and solid polymer fuel cell using the same,
JP2007207718A (en) * 2006-02-06 2007-08-16 Tokai Univ Separator for fuel cell and its manufacturing method
JP2008004540A (en) * 2006-05-22 2008-01-10 Toyota Central Res & Dev Lab Inc Amorphous carbon film, method for forming amorphous carbon film, electroconductive member comprising amorphous carbon film, and fuel cell separator
JP2008041253A (en) * 2006-08-01 2008-02-21 Nissan Motor Co Ltd Electrocatalyst and power generation system using the same
JP2008153200A (en) 2006-11-20 2008-07-03 Gunze Ltd Electrode for solid polymer fuel cell, manufacturing method of solid polymer fuel cell, and solid polymer fuel cell
JP2008222545A (en) * 2007-03-09 2008-09-25 Samsung Electronics Co Ltd Transparent electrode containing carbon nanotube and its production method
JP2008300133A (en) 2007-05-30 2008-12-11 Toyota Motor Corp Method for manufacturing fuel cell
JP2008301309A (en) 2007-06-01 2008-12-11 Panasonic Corp Encoding rate control method, transmission apparatus to control encoding rate, program storage medium, and integrated circuit
JP2008303217A (en) 2001-11-30 2008-12-18 Schering Corp ADENOSINE A2a RECEPTOR ANTAGONIST
JP2008303223A (en) 1998-10-21 2008-12-18 Shire Llc Oral pulsed dose drug delivery system
JP2008303219A (en) 1996-06-03 2008-12-18 Basell Polyolefine Gmbh Chemical compound and synthetic method
JP2009142600A (en) 2007-12-18 2009-07-02 Toshiba Corp Ultrasonic diagnostic apparatus and control method of the same
JP2009238497A (en) * 2008-03-26 2009-10-15 Nissan Motor Co Ltd Fuel cell separator

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0756795B2 (en) 1986-05-30 1995-06-14 シャープ株式会社 Electrode for non-aqueous secondary battery
US5747185A (en) 1995-11-14 1998-05-05 Ztek Corporation High temperature electrochemical converter for hydrocarbon fuels
KR100453597B1 (en) * 1998-06-30 2004-10-20 마쯔시다덴기산교 가부시키가이샤 Solid polymer electrolyte fuel cell
JP3600503B2 (en) * 2000-04-19 2004-12-15 トヨタ自動車株式会社 Fuel cell separator, method of manufacturing fuel cell separator, and fuel cell
JP4974495B2 (en) * 2004-09-21 2012-07-11 勝 堀 FUEL CELL SEPARATOR, FUEL CELL ELECTRODE STRUCTURE, METHOD FOR PRODUCING THEM, AND SOLID POLYMER FUEL CELL HAVING THE SAME
US20080057371A1 (en) * 2005-05-25 2008-03-06 Hitachi Cable, Ltd. Separator for Fuel Cell and Method for Producing Same
RU2319256C1 (en) 2006-04-26 2008-03-10 Некоммерческая организация Учреждение Институт проблем химической физики Российской академии наук (статус государственного учреждения) ИПХФ РАН Fuel cell
US8119242B2 (en) 2006-05-22 2012-02-21 Kabushiki Kaisha Toyota Chuo Kenkyusho Amorphous carbon film, process for forming amorphous carbon film, conductive member provided with amorphous carbon film, and fuel cell separator

Patent Citations (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2008303219A (en) 1996-06-03 2008-12-18 Basell Polyolefine Gmbh Chemical compound and synthetic method
JPH1087396A (en) * 1996-09-10 1998-04-07 Sumitomo Electric Ind Ltd Hard carbon film
JPH1149506A (en) * 1997-07-31 1999-02-23 Kyocera Corp Ornamental member
JP2000067881A (en) * 1998-08-24 2000-03-03 Honda Motor Co Ltd Separator for fuel cell
JP2008303223A (en) 1998-10-21 2008-12-18 Shire Llc Oral pulsed dose drug delivery system
JP2002327271A (en) * 2001-04-27 2002-11-15 Sumitomo Electric Ind Ltd Electroconductive hard carbon film
JP2008303217A (en) 2001-11-30 2008-12-18 Schering Corp ADENOSINE A2a RECEPTOR ANTAGONIST
JP2004185998A (en) 2002-12-04 2004-07-02 Toyota Motor Corp Separator for fuel cell
JP2006286457A (en) 2005-04-01 2006-10-19 Toyota Motor Corp Manufacturing method of fuel cell separator
JP2007165275A (en) * 2005-04-28 2007-06-28 Kurimoto Ltd Separator, manufacturing method of separator and solid polymer fuel cell using the same,
JP2007134107A (en) 2005-11-09 2007-05-31 Toyota Motor Corp Separator for fuel cell, its manufacturing method and fuel cell
JP2007207718A (en) * 2006-02-06 2007-08-16 Tokai Univ Separator for fuel cell and its manufacturing method
JP2008004540A (en) * 2006-05-22 2008-01-10 Toyota Central Res & Dev Lab Inc Amorphous carbon film, method for forming amorphous carbon film, electroconductive member comprising amorphous carbon film, and fuel cell separator
JP2008041253A (en) * 2006-08-01 2008-02-21 Nissan Motor Co Ltd Electrocatalyst and power generation system using the same
JP2008153200A (en) 2006-11-20 2008-07-03 Gunze Ltd Electrode for solid polymer fuel cell, manufacturing method of solid polymer fuel cell, and solid polymer fuel cell
JP2008222545A (en) * 2007-03-09 2008-09-25 Samsung Electronics Co Ltd Transparent electrode containing carbon nanotube and its production method
JP2008300133A (en) 2007-05-30 2008-12-11 Toyota Motor Corp Method for manufacturing fuel cell
JP2008301309A (en) 2007-06-01 2008-12-11 Panasonic Corp Encoding rate control method, transmission apparatus to control encoding rate, program storage medium, and integrated circuit
JP2009142600A (en) 2007-12-18 2009-07-02 Toshiba Corp Ultrasonic diagnostic apparatus and control method of the same
JP2009238497A (en) * 2008-03-26 2009-10-15 Nissan Motor Co Ltd Fuel cell separator

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See also references of EP2357655A4 *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102082277A (en) * 2010-12-24 2011-06-01 上海交通大学 Metal gas diffusion layer used for fuel cell and preparation method thereof

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